Earth pressure management system

Abstract

By installing a pore water pressure gauge at a position where it can directly contact the natural ground instead of the inner partition wall of the chamber - for example, on the side surface of the shield skin plate - it is possible to always accurately measure the groundwater pressure during shield tunneling and properly manage the control earth pressure, thus providing an earth pressure management system. 【Solution means】An earth pressure management system for a shield tunneling machine, comprising: an earth pressure gauge 22 for measuring the earth pressure in the chamber 16; a pore water pressure gauge 24 for measuring the pore water pressure outside the chamber 16; and a setting unit 40 for setting the control earth pressure based on the measured earth pressure and pore water pressure. This pore water pressure gauge 24 is embedded in the surface of the skin plate 2. Further, the pore water pressure gauge 24 is embedded near the height of the central axis of the earth pressure shield 1 as a shield tunneling machine on the surface of the skin plate 2.

Description

Technical Field

[0001] The present invention relates to an earth pressure management system applied to a shield tunneling machine.

Background Art

[0002] Conventionally, the management of the earth pressure in the chamber of an earth pressure shield is essential for tunneling the shield while maintaining the stability of the face and preventing deformation and settlement of the surrounding ground. By performing appropriate management, the displacement of the surrounding ground can be suppressed.

[0003] Normally, the earth pressure control in the chamber of an earth pressure shield is performed using the value of an earth pressure gauge attached to the partition wall. Specifically, the management value of the earth pressure in the chamber is set with (groundwater pressure + active earth pressure + α) or (groundwater pressure + at-rest earth pressure) as the lower limit value. This groundwater pressure and earth pressure are calculated based on the groundwater level and soil constants obtained from prior investigations.

[0004] The values obtained from such prior investigations are the values at the pinpoint soil investigation boring points and are obtained from about one boring investigation per 100 m of the shield construction route. For example, the soil constants (C, φ, unit weight, etc.) may differ from the values at the actual tunneling points. Also, regarding the groundwater pressure, there is a possibility of variation due to the difference between the boring investigation time and the shield tunneling time and the influence of rainfall, etc. Furthermore, it is considered that the groundwater pressure is not simply limited to the relationship between the groundwater level and the depth of the shield, but is also greatly affected by the presence of an aquiclude such as confined water and viscous soil existing in the middle.

[0005] On the other hand, the earth pressure gauge in an earth pressure shield is usually attached to the partition wall to measure the earth pressure in the chamber. Inside the chamber of the earth pressure shield, the excavated soil is made muddy and plastically fluidized and has water stoppage properties. Therefore, the value indicated by the earth pressure gauge becomes the value obtained by adding the effective earth pressure and the groundwater pressure, and it has become difficult to accurately measure the groundwater pressure - that is, the pore water pressure other than the effective earth pressure.

[0006] On the other hand, it is not uncommon for the groundwater level to change over the years due to changes in rainfall and the amount of groundwater pumped, and changes of nearly 10 m over 10 years have been reported. Furthermore, seasonal water level changes also occur. In addition, rapid changes in the groundwater level due to regional heavy rainfall have also occurred. As described above, the value indicated by the diaphragm earth pressure gauge at the time of shield stop in an earth pressure shield is the earth pressure in the chamber, and the earth pressure is the sum of the active earth pressure and the pore water pressure at the face. However, as a prerequisite for this, it is necessary for the chamber to be filled with earth.

[0007] In addition, in places where the ground being excavated has a high permeability coefficient such as a sand layer, the water pressure around the face may be affected by the earth pressure in the chamber. Specifically, the pore water pressure gauge installed to measure the groundwater pressure around the face indicates the groundwater pressure around the face when the earth pressure in the chamber is lower than the surrounding groundwater pressure, but may indicate a measured value equal to or higher than the surrounding groundwater pressure when the earth pressure in the chamber is equal to or higher than the surrounding groundwater pressure. This influence is greater the closer it is to the face, and approaches and converges to the surrounding groundwater pressure value as it moves away. Furthermore, the surrounding groundwater pressure that was affected by the earth pressure in the chamber gradually approaches and converges to the surrounding groundwater pressure value immediately after the shield excavation is stopped.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the case where the groundwater level has risen during the construction stage as a result of a preliminary survey, and the originally planned managed earth pressure is not an appropriate value and the face cannot be maintained, the face will collapse, the ground above will loosen, and the chamber will not be filled with earth (see Fig. 8).

[0010] At this time, for example, only almost the groundwater pressure acts on the earth pressure gauge (D1, see Fig. 8) attached above the partition wall. Also, even for the earth pressure gauge (D2, see Fig. 8) attached near the center or below, the earth pressure of the loosened earth and sand (S) acts instead of the original active earth pressure. In this case, the value indicated by the earth pressure gauge on the partition wall will not be the original (active earth pressure + groundwater pressure), but will show a smaller value (that is, the groundwater pressure or a value close to it).

[0011] If the shield manager is not aware that the chamber is not filled with earth, there is a high possibility of misrecognizing the value indicated by the earth pressure gauge as (active earth pressure + groundwater pressure). Then, in this case, tunneling will continue at an earth pressure lower than the required managed earth pressure, and as a result, the surrounding ground may loosen, and ultimately the ground surface may subside.

[0012] Therefore, an object of the present invention is to provide an earth pressure management system that can always accurately measure the groundwater pressure during shield tunneling and appropriately manage the managed earth pressure by installing a pore water pressure gauge at a position where it can directly contact the ground - for example, on the side surface of the shield skin plate - instead of on the partition wall inside the chamber.

[0013] Furthermore, as described in the background art, the groundwater pressure around the face may be affected by the earth pressure inside the chamber, resulting in inaccurate measured values.

[0014] Therefore, an object of the present invention is to provide an earth pressure management system that can be appropriately managed with a managed earth pressure equal to or higher than (active earth pressure + groundwater pressure value) by installing at least one or more pore water pressure gauges on the side surface of the skin plate.

Means for Solving the Problem

[0015] To achieve the above object, the earth pressure management system of the present invention is an earth pressure management system in a shield tunneling machine, comprising an earth pressure gauge for measuring the earth pressure in the chamber, at least one or more pore water pressure gauges for measuring the groundwater pressure outside the chamber, and a setting unit for setting a managed earth pressure based on the measured earth pressure and groundwater pressure.

Effect of the Invention

[0016] Thus, the earth pressure management system of the present invention is an earth pressure management system in a shield tunneling machine, comprising an earth pressure gauge for measuring the earth pressure in the chamber, at least one or more pore water pressure gauges for measuring the groundwater pressure outside the chamber, and a setting unit for setting a managed earth pressure based on the measured earth pressure and groundwater pressure. With such a configuration, it is possible to always accurately measure the groundwater pressure during shield tunneling and appropriately manage the managed earth pressure.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the components described in the following examples are illustrative, and are not intended to limit the technical scope of the present invention thereto. Hereinafter, the earth pressure shield 1 will be described as an example, but the present invention can also be applied to other types of shield tunneling machines.

Example

[0019] (Configuration of Shield Tunneling Machine) As shown in the cross-sectional view of FIG. 1, the earth pressure shield 1 as the shield tunneling machine of the present embodiment includes a skin plate (shield main body cylinder) 2, a bulkhead 3, a cutter head 5, a cutter rotating shaft 10, a cutter drive unit 12, a chamber 16, an earth discharging device 17, a shield propulsion jack 18, a bentonite material supply pipe 21, an earth pressure gauge 22, a pore water pressure gauge 24, ···, and a setting unit (control unit) 40 arranged inside the operation room and the like.

[0020] The cutter head 5 has cutter spokes 51, a plurality of cutter bits 52 provided on the front surface of the cutter spokes 51, ···, a fishtail bit 53 provided at the center of the front surface of the cutter spokes 51, and a plurality of stirring blades 54 provided on the back surface of the cutter spokes 51, ···. The cutter head 5 is integrally attached to the cutter rotating shaft 10.

[0021] The cutter rotating shaft 10 is rotatably supported by a bearing 11 provided on the bulkhead 3 and a bearing provided at the rear part of a gear box 13 described later. The cutter rotating shaft 10 is connected to the cutter drive unit 12. The cutter drive unit 12 includes a gear box 13 installed on the back side of the bulkhead 3, a rotary drive source 14 connected to the gear box 13, and a reduction gear (arranged in the gear box 13; not shown) interposed between the output shaft of the rotary drive source 14 and the cutter rotating shaft 10.

[0022] The chamber 16 is formed in the space surrounded by the hood portion 2a of the skin plate 2, the partition wall 3, and the face F. As the earth discharging device 17, for example, a screw conveyor is used. The earth intake port in the earth discharging device 17 is opened and installed so as to face the chamber 16.

[0023] Furthermore, an erector 15 for assembling the segment 90 is installed at the tail portion 2b of the skin plate 2. Furthermore, a plurality of shield propulsion jacks 18 are installed inside the skin plate 2 at required intervals in the circumferential direction. In addition, a tail seal 19 is provided at the rear end portion of the skin plate 2.

[0024] As described above, the earth pressure type shield 1 as the shield tunneling machine of the present embodiment includes an earth pressure gauge 22 for measuring the earth pressure in the chamber 16, and a plurality of pore water pressure gauges 24 for measuring the groundwater pressure outside the chamber 16, that is, the pore water pressure, ···. As shown in the perspective view of FIG. 2, these pore water pressure gauges 24, ··· are provided with recesses on the surface of the skin plate 2 and at least one or more are embedded. Specifically, four pore water pressure gauges 24, ··· are arranged at equal intervals in the direction away from the face F (in the shaft mouth direction) and at the same height (level). Of course, the number of pore water pressure gauges 24 is not limited to four, and one or more are sufficient. When a plurality are installed, it is preferable to provide them at equal intervals in the shaft mouth direction from the face F. These pore water pressure gauges 24, ··· are embedded near the height of the central axis of the earth pressure type shield 1 as the shield tunneling machine on the surface of the skin plate 2. That is, the pore water pressure gauges 24, ··· are arranged on the side surface of the skin plate 2 facing the horizontal direction. Furthermore, it is also possible to provide pore water pressure gauges 24, ··· at a plurality of different heights.

[0025] Furthermore, the pore water pressure gauge installed on the skin plate can be provided with a telescopic operating mechanism using a jack or the like in the outer peripheral direction, or by arranging a shutter-type slide hatch or the like on the surface portion of the water pressure measurement location, it is also effective to prevent the influence during water pressure measurement by the earth and backfill material or the like that has entered the tail void generated by overcutting.

[0026] Also, as another embodiment of the pore water pressure gauge (24), it can be attached to the tip of a forward measuring device configured to be telescopically extendable from the partition wall 3 to the front of the face F to measure the pore water pressure in front of the face F. More specifically, the forward measuring device (forward exploration device) can be, for example, a rod-shaped measuring device that can be extended and retracted (extended and retracted from the position of the partition wall 3 to the position in front of the face F) by a hydraulic jack. In this case, as the timing of measurement, it is preferably when the cutter head 5 is stopped during segment assembly.

[0027] In addition, the earth pressure shield 1 further includes a setting unit 40. The setting unit 40 is, for example, a general-purpose personal computer having a memory, a CPU, an SSD, etc. In the setting unit 40, the control earth pressure of the earth pressure shield 1 is set to control tunneling. That is, during tunneling, the earth pressure shield 1 is advanced by the shield propulsion jack 18, the muck is discharged by the muck removal device 17 (screw conveyor), and at the same time, the earth pressure is measured by the earth pressure gauge 22.

[0028] It should be noted that the function of the setting unit 40 described later can of course be executed by a setting unit (arithmetic unit; personal computer) separate from the setting unit 40 that controls the tunneling of the earth pressure shield 1. And, as shown in the block diagram of FIG. 3, the earth pressure management system S of the present invention is constituted by the earth pressure gauge 22, a plurality of pore water pressure gauges 24,..., and the setting unit 40 that sets the active earth pressure and groundwater pressure that are the reference for excavation.

[0029] As a functional part, the setting unit 40 has a function of calculating assumed values (assumed active earth pressure and assumed groundwater pressure) of the active earth pressure and groundwater pressure, which are calculation elements of the control earth pressure, based on the soil constants, soil cover, and groundwater level. Further, as will be described later, it has a function of correcting (resetting) these values based on the groundwater pressure measured by the pore water pressure gauges 24,....

[0030] That is, on the operation panel (management screen) for tunneling management, the value of the management earth pressure and its breakdown (for example, the assumed active earth pressure, the assumed groundwater pressure, and the margin value) are displayed. Here, the initial values of the assumed active earth pressure and the assumed groundwater pressure are values that reflect the soil constants, soil cover, and groundwater level that vary depending on the tunneling location. These values are the calculated values based on the initial plan. In addition, the earth pressure inside the chamber 16 measured by the earth pressure gauge 22 is also displayed.

[0031] And the earth pressure type shield 1 as the shield tunneling machine of this embodiment is provided with a pore water pressure gauge 24 that directly measures the groundwater pressure outside the chamber 16, and the measured value by the pore water pressure gauge 24 is also displayed on the management screen. In this way, it becomes possible to compare the planned groundwater pressure with the actual groundwater pressure, and it becomes possible to generally judge whether the current management earth pressure value is appropriate. Just by showing the values as described above on the operation panel (management screen), it is possible to judge the suitability of the pressure, but furthermore, the suitability of the planned groundwater pressure and the actual groundwater pressure can be judged by, for example, a management PC 60, etc., to issue a warning alarm or stop the shield.

[0032] In addition, when a plurality of pore water pressure gauges 24 for directly measuring the groundwater pressure, ··· are provided, the measured values by the pore water pressure gauges 24, ··· are also respectively displayed on the management screen. By doing so, it becomes possible to compare the groundwater pressure values corresponding to the locations where the respective pore water pressure gauges 24 are installed, and it becomes possible to compare the groundwater pressure around the face with the earth pressure of the soil in the chamber. Specifically speaking, as will be described later, if the values of the pore water pressure gauges 24, ··· tend to decrease as the distance from the face position increases, it means that the earth pressure in the chamber is being excavated at a management earth pressure higher than the (groundwater pressure + effective active earth pressure) around the face. On the other hand, if the measured values of the pore water pressure gauges 24, ··· show substantially the same value, there is a possibility that the earth pressure in the chamber is being excavated at a management earth pressure lower than the (groundwater pressure + effective active earth pressure) around the face - in other words, there is a possibility that excavation is being carried out in a dangerous state. On the operation panel (management screen), when the measured values of the pore water pressure gauges 24, ··· are the same, that is, when the (groundwater pressure + effective active earth pressure) around the face (outside) is higher than the earth pressure in the chamber, for example, the suitability can be judged by a management PC 60 or the like, and a warning alarm can be issued or the shield can be stopped.

[0033] (Function - Part 1 -) Next, the procedure for setting the management earth pressure using the earth pressure management system S of this embodiment will be described with reference to the flowchart of FIG. 4. As shown in FIG. 4, the earth pressure management system S is realized by executing the following steps S1 to S7.

[0034] In advance, after measuring the soil composition, soil constants, soil cover, and groundwater level through a preliminary survey (step S1), an initial plan is made (step S2). Specifically speaking, based on the measurement results of the preliminary survey, [planned management earth pressure = planned effective active earth pressure + planned groundwater pressure + planned margin value (in the initial plan, calculated according to the conditions based on the preliminary survey)] is calculated (step S3).

[0035] Then, as the initial value of [Set Management Earth Pressure = Set Active Earth Pressure + Set Groundwater Pressure + Set Margin Value (value to be adopted during construction)], the [Plan Management Earth Pressure = Planned Active Earth Pressure + Planned Groundwater Pressure + Planned Margin Value (calculated based on conditions from preliminary surveys in the initial plan)] calculated earlier is set (Step S4).

[0036] Separate from the above initial value setting process, shield tunneling is being carried out (Step S5). And during tunneling, the Y (Yes) / N (No) of the following Judgment A is determined (Step S6).

[0037] <Judgment A> When (Set Groundwater Pressure - α1) ≤ Pw ≤ (Set Groundwater Pressure + α2), it is judged as Yes, so the process proceeds to Step S4 and tunneling continues. Here, Pw is the groundwater pressure measured by the pore water pressure gauge 24, and α1 and α2 are constants.

[0038] When Pw < (Set Groundwater Pressure - α1) or (Set Groundwater Pressure + α2) < Pw, it is judged as No, so the process proceeds to Step S7. α1 and α2 in this judgment formula are set according to the situation within the range of 0 to the set margin value. At this time, α1 and α2 may be the same value or different values.

[0039] And the management earth pressure is reset (Step S7). 1) When Pw < (Set Groundwater Pressure - α1): It is judged that the actual groundwater pressure is lower than the assumed set groundwater pressure, so the set groundwater pressure included in the set management earth pressure is changed to a value reduced by β1. Here, β1 is a constant.

[0040] 2) When (Set Groundwater Pressure + α2) < Pw: It is judged that the actual groundwater pressure is higher than the assumed set groundwater pressure, so the set groundwater pressure included in the set management earth pressure is changed to a value increased by β2. Here, β2 is a constant.

[0041] In this earth pressure reset, β1 and β2 are respectively set according to the situation within the range of ((the difference between the set groundwater pressure and Pw) / 5) to (the difference between the set groundwater pressure and Pw). At this time, β1 and β2 may have the same value or different values.

[0042] The setting of the values of α1 and α2 in Judgment A is the value of how much difference between the set groundwater pressure and the actual groundwater pressure is allowed. In cases where the soil cover is shallow or the soil is soft cohesive soil sensitive to changes in earth pressure, setting methods such as setting relatively small values can be considered. Conversely, in cases where the soil cover is large or the ground is hard, there are also setting methods with relatively large values that do not require frequent resetting.

[0043] Also, the setting of the values of β1 and β2 in the managed earth pressure reset is the value of how much time it takes to correct the difference between the set value and the measured value of the groundwater pressure. If β1 to β2 are set as the difference between the set groundwater pressure and Pw, it can be made the same value (difference is 0) in one correction, but in some cases, it may cause a sudden correction of the set value, resulting in an impact on the surrounding ground. It is desirable to set the value of β according to how often a series of Judgment A and managed earth pressure reset are performed.

[0044] (Action - Part 2 - ) Next, another setting procedure for the managed earth pressure using the earth pressure management system S of this embodiment will be described with reference to another flowchart in FIG. 5 and FIG. 6. As shown in FIG. 5, the earth pressure management system S is realized by executing steps S1 to S7. Among these, for the processes other than steps S6 and S7, since they are substantially the same as those described in (Action - Part 1 - ) using FIG. 4, the description will be omitted.

[0045] And in this another setting procedure, during tunneling, Y (Yes) / N (No) of the following Judgment B is executed (step S6). <Judgment B> That is, the setting unit 40 is configured to consider resetting the managed earth pressure based on the following conditions. P w1 >P wnCase: Do not reset - Pattern 1 P w1 =···=P wn Case: Consider reset - Pattern 2 Here, P wn is the water pressure measured by the pore water pressure gauge, n is a natural number of 2 or more, and is set to 1, 2, ···, n in order from the side closer to the face.

[0046] Regarding Pattern 1, depending on the ground conditions, the measurement values of the pore water pressure gauges (when three or more are installed) may result in the following. 1) P w1 >···>P wn 2) P w1 >P w2 =··P wn 3) P w1 =P w2 >··P wn 4) P w1 =P w2 >P w3 =··P wn 5) P w1 >P w2 =P w3 >P wn In addition, there are several cases depending on the number of installed pore water pressure gauges. Even in the above cases, if (P w1 >P wn ) is satisfied, it is judged as Pattern 1.

[0047] Also, since the measured value of the pore water pressure includes measurement error, (P w(n-1) <P wn ), (P w(n―2) <P w(n-1) >P wn ) and other measurement results may be obtained. Assuming a situation where such an unclear situation occurs in such a judgment, for example, (0.5 kN / m 2It is desirable to adopt a form in which ) is used as a criterion for judgment of measurement error (allowable value of width). Since this criterion for judgment of measurement error is affected by ground conditions, the installation interval of the pore water pressure gauges, etc., it is desirable to set it according to each condition. Furthermore, by performing linear regression on the results of the pore water pressure measurements (P w1 ···P wn ), it may be possible to judge whether the measurement accuracy is correct based on the standard deviation of the straight line.

[0048] Specifically, when P wn >P wn (pattern 1), the control earth pressure is not reset. That is, if the water pressure values indicated by the pore water pressure gauges 24, ··· decrease as they get farther from the face position, it means that the plastic-fluidized earth pressure in the chamber 2 is advancing at a control earth pressure higher than the (groundwater pressure + effective active earth pressure) around the face. This can be said to be an appropriate state.

[0049] On the other hand, when P w1 =···=P wn (pattern 2), consideration is given to resetting the control earth pressure. That is, if the water pressure values indicated by the pore water pressure gauges 24, ··· show the same value respectively, there is a possibility that the plastic-fluidized earth pressure in the chamber 2 is advancing at a control earth pressure lower than the (groundwater pressure + effective active earth pressure) around the face. In other words, there is a possibility that tunneling is being carried out in a dangerous state. The reason for re-examining in this way is that in a ground with a particularly high permeability coefficient, the measured values of the pore water pressure gauge 24 (P w1 ·P w2 ·P w3 ···P wn ) may not show a difference over a distance of about the length of the shield machine.

[0050] In the case of pattern 2, resetting of the control earth pressure is considered (step S7). First, observe the temporal change of the measured value after tunneling stop of the pore water pressure gauge 24 arranged closest to the face. Then, classify it into the following two patterns and take corresponding measures.

[0051] (Pattern 2-1) When the measured value of the pore water pressure gauge gradually decreases over time after stopping ⇒ It is judged that it is affected by the soil pressure in the chamber Soil pressure in the chamber > (groundwater pressure + effective active earth pressure) (do not reset)

[0052] (Pattern 2-2) When the measured value of the pore water pressure gauge does not change over time after stopping ⇒ It is judged that it is not affected by the soil pressure in the chamber Soil pressure in the chamber ≤ (groundwater pressure + effective active earth pressure) (reset)

[0053] In the case of "Pattern 2-2", change the set control earth pressure to a value increased by γ1. Let γ1 be a constant. Here, the constant γ1 to be increased is set according to the ground conditions respectively. The following shows an example of setting γ1. The set value of the control earth pressure is often set as follows. (Control earth pressure) = (effective active earth pressure) + (groundwater pressure) + (margin value) Taking this (margin value) as a reference, set γ1 within the following range. γ1: (margin value) / 5 ~ (margin value) After that, resume tunneling with the control earth pressure increased by γ1, and by checking the measured value of the pore water pressure gauge again at step S6 when the next tunneling stops, tunneling with a more appropriate control earth pressure becomes possible.

[0054] · Note that even when only one pore water pressure gauge 24 is installed, by checking the change over time of the measured value of the pore water pressure gauge 24 at the time of tunneling stop, it is possible to estimate the relationship between (soil pressure in the chamber) and (groundwater pressure + effective active earth pressure).

[0055] When the measured values of the pore water pressure gauge 24, etc. are substantially the same - that is, when the groundwater pressure + effective active earth pressure around the face (outside) is higher than the chamber earth pressure - and further, when the measured value of the pore water pressure gauge during the stop of tunneling does not decrease over time - for example, the suitability can be judged by a management PC 60 or the like, and a warning alarm (warning level 1, warning level 2) can be issued, or the shield tunneling can be stopped according to the level.

[0056] (Application example) The following table shows the simplest calculation example of the management earth pressure.

Table 1

[0057] Here, as shown in Fig. 7, a calculation example is shown in the case where the groundwater level at the planning stage was 40 (m) from the shield center position, but became 45 (m) during the actual construction. The unit volume weight, internal friction angle, adhesion, etc. of the soil are estimated from the boring data at the planning stage.

[0058] When the groundwater pressure and the effective active earth pressure calculated at the planning stage are added together, it becomes 552 (kN / m at the shield center position 2 ) and if α is 20 (kN / m 2 ) then the management earth pressure is 572 (kN / m 2 ). In the actual construction, assuming that the groundwater level has changed from the planning stage and is 45 (m) from the shield center position, the combined value of the groundwater pressure and the effective active earth pressure is 591 (kN / m 2 ) and it exceeds the management earth pressure of 572 (kN / m 2 ). In this case, if construction continues at the management earth pressure of 572 (kN / m 2 ) at the planning stage, the face cannot be held by the pressure in the chamber and the ground will subside.

[0059] On the other hand, in the present invention, by directly measuring the groundwater pressure, the groundwater pressure during construction is 450 (kN / m 2) will be measured. At this point, since it is found that the initial planned groundwater pressure has changed, it becomes possible to recalculate the management earth pressure. As a result, the management earth pressure is calculated as 611 (kN / m 2 ) and can exceed the combined value of the groundwater pressure and the effective active earth pressure, which is 591 (kN / m 2 ).

[0060] In the earth pressure management of an earth pressure shield, since (groundwater pressure + active earth pressure + margin α) is used as the management value, during tunneling, it is not recognized what numerical value the groundwater pressure among the management values is. Therefore, it is not possible to compare the value indicated by the earth pressure gauge with the actual groundwater pressure. As a result, tunneling will continue with the wrong management earth pressure.

[0061] Here, what is important is that when the ground in front loosens and the inside of the chamber 16 is not filled with mud, the earth pressure gauge 22 attached to the partition wall 3 will not show the value of (active earth pressure + groundwater pressure) at the face. Even in such a situation, the shield manager will mistakenly recognize that the value indicated by the earth pressure gauge is (active earth pressure + groundwater pressure), and the situation cannot be improved.

[0062] (Effect) Next, the effects of the earth pressure management system S of this embodiment will be described while enumerating them.

[0063] (1) As described above, the earth pressure management system S of this embodiment is an earth pressure management system S in a shield tunneling machine, and includes an earth pressure gauge 22 for measuring the earth pressure of the mud inside the chamber 16, a pore water pressure gauge 24 for measuring the groundwater pressure outside the chamber 16, and a setting unit 40 for setting the management earth pressure based on the measured earth pressure and groundwater pressure. With such a configuration, during shield tunneling, the groundwater pressure can always be accurately measured and the management earth pressure can be properly managed. That is, it overcomes the problems that could not be fully addressed by the conventional boring survey and the earth pressure gauge 22 on the partition wall 3, and can realize the improvement of the efficiency and quality of the tunneling work.

[0064] That is, if the groundwater pressure at the shield position is constantly measured, even if the originally assumed groundwater level has actually fluctuated from that point or there are effects such as the influence of confined water, the groundwater pressure acting on the face can be accurately measured.

[0065] The managed earth pressure may be set as (active earth pressure + groundwater pressure + α) used in the original earth pressure management. Since the value of the groundwater pressure at this time is the actually measured value, the influence caused by the fluctuation of the groundwater pressure is eliminated. On the other hand, since the soil cover can be clearly determined from the ground surface height and the depth of the shield, the assumed effective earth pressure obtained from the soil investigation does not fluctuate extremely.

[0066] (2) Since the pore water pressure gauge 24 in this embodiment is installed on the surface of the skin plate 2, the pore water pressure outside the chamber 16 can be measured.

[0067] (3) Also, since the pore water pressure gauge 24 is installed near the height of the central axis of the earth pressure shield 1 as a shield tunneling machine on the surface of the skin plate 2, it is hardly affected by the soil cover, and since the initial planned value and the measured value are calculated and displayed on the same basis, it is easy to understand. The pore water pressure gauge 24 may be arranged at a height other than the central axis, or may be installed at the tip of a measuring device that expands and contracts toward the face F side. Furthermore, the pore water pressure gauge 24 can penetrate to the outside of the tail void using a telescopic mechanism such as a jack, or by installing a shutter-type cover at the measurement location of the pore water pressure gauge 24, the accurate groundwater pressure can be grasped without being affected by the soil and backfill materials that have come around from the face or the backfill injection holes.

[0068] (4) Furthermore, since at least two or more pore water pressure gauges 24,... are installed on the surface of the skin plate 2, it becomes possible to determine whether the set value of the managed earth pressure is appropriate based on the change tendency of the groundwater pressure.

[0069] (5) Further, at least two or more (four in the embodiment) pore water pressure gauges 24,... are arranged at equal intervals in the heading direction from the face at the same height, so that it is extremely easy to determine whether the set value of the control earth pressure is appropriate based on the change tendency of the groundwater pressure.

[0070] (6) Since the setting unit 40 is configured to reset the control earth pressure based on the change of the pore water pressure over time, it is extremely easy to determine whether the set value of the control earth pressure is appropriate. Specifically, for example, when the measured value of the pore water pressure gauge during shield tunneling stop gradually decreases over time, no resetting is performed. When there is no change over time, resetting is performed. It can be set like this.

[0071] (7) Further, it is preferable that the setting unit 40 is configured to set the control earth pressure based on the following (Formula 1). (Formula 1) Set control earth pressure = Set effective active earth pressure + Set groundwater pressure + Set margin value If set in this way, since the control earth pressure can be calculated based on the sum of the effective active earth pressure and the groundwater pressure outside the chamber 16, it is possible to always accurately measure the groundwater pressure during tunneling and set the control earth pressure appropriately.

[0072] (8) Further, it is preferable that the setting unit 40 is configured to reset the control earth pressure based on the following (Formula 2). Here, α1 and α2 are constants. (Formula 2) When (Set groundwater pressure - α1) ≤ Pw ≤ (Set groundwater pressure + α2): Do not reset When Pw < (Set groundwater pressure - α1) or (Set groundwater pressure + α2) < Pw: Reset If set in this way, when the measured groundwater pressure deviates significantly from the set groundwater pressure, the set groundwater pressure can be reset, so that it is possible to always accurately set the groundwater pressure during tunneling and set the control earth pressure appropriately.

[0073] (9) Further, it is preferable that the setting unit 40 is configured to reset the controlled earth pressure based on the following (Equation 3). Here, β1 and β2 are constants. (Equation 3) When Pw < (set groundwater pressure - α1): Decrease the set groundwater pressure by β1 When (set groundwater pressure + α2) < Pw: Increase the set groundwater pressure by β2 If set in this way, a sudden change (correction) in the set groundwater pressure can be suppressed.

[0074] (10) Also, it is preferable that the setting unit 40 is configured to reset the controlled earth pressure based on the following (Equation 4). Here, P wn is the water pressure measured by the pore water pressure gauge 24, ···, and n is a constant, and is set to 1, 2, ···, n in order from the closest to the face. (Equation 4) P w1 > P wn Case: Do not reset the controlled earth pressure P w1 = ··· = P wn Case: Consider resetting the controlled earth pressure If the presence or absence of reset consideration can be automatically determined based on a plurality of water pressure values in this way, it becomes extremely easy to determine whether the set value of the controlled earth pressure is appropriate based on the change tendency of the measured water pressure value.

[0075] And when considering resetting: When the measured value of the pore water pressure gauge during shield tunneling stop gradually decreases over time, do not reset; when it does not change over time, reset. That is, it is preferable that the setting unit 40 is linked to the groundwater pressure measurement value of the pore water pressure gauge during shield tunneling stop, and sets the controlled earth pressure based on the change tendency over time. If the presence or absence of reset can be automatically determined based on the measured value of the pore water pressure gauge at the time of tunneling stop in this way, it becomes extremely easy to determine whether the set value of the controlled earth pressure is appropriate based on the measured value of the measured pore water pressure gauge.

[0076] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention.

Explanation of Signs

[0077] 1: Earth pressure shield 2: Skin plate 2a: Hood part 2b: Tail part 3: Partition wall 5: Cutter head 10: Cutter rotation shaft 11: Bearing 12: Cutter drive unit 13: Gear box 14: Rotation drive source 15: Erector 16: Chamber 17: Earth discharging device 18: Shield propulsion jack 19: Tail seal 21: Working soil material supply pipe 22: Earth pressure gauge 24: Pore water pressure gauge 40: Setting unit 43: Communication cable 51: Cutter spoke 52: Cutter bit 53: Fish tail bit 54: Agitating blade 60: Management PC 90: Segment S: Earth pressure management system F: Face

Claims

1. An earth pressure management system for a shield tunneling machine, comprising: An earth pressure gauge for measuring the earth pressure inside the chamber; A pore water pressure gauge for measuring only the pore water pressure outside the chamber; A setting unit for setting a management earth pressure based on the measured pore water pressure. When the measured groundwater pressure deviates significantly from the set groundwater pressure, the setting unit resets the set groundwater pressure, and sets the management earth pressure based on the following formula (1): An earth pressure management system. (Formula 1) Set management earth pressure = Planned effective active earth pressure + Set groundwater pressure + Set margin value Here, the planned effective active earth pressure is calculated based on the measurement results of the preliminary investigation.

2. The pore water pressure gauge according to claim 1, which is installed on the surface of the skin plate.

3. The pore water pressure gauge according to claim 2, which is installed near the height of the central axis of the shield tunneling machine on the surface of the skin plate.

4. The setting unit according to any one of claims 1 to 3, which resets the management earth pressure based on the change of the pore water pressure over time.

5. An earth pressure management system for a shield tunneling machine, comprising: An earth pressure gauge for measuring the earth pressure inside the chamber; At least two or more pore water pressure gauges for measuring only the pore water pressure outside the chamber; A setting unit for setting a management earth pressure based on the measured pore water pressure. The setting unit sets the management earth pressure based on the following formula (1) based on the change trend of the measured groundwater pressure: An earth pressure management system. (Formula 1) Set management earth pressure = Planned effective active earth pressure + Set groundwater pressure + Set margin value Here, the planned effective active earth pressure is calculated based on the measurement results of the preliminary investigation.

6. The at least two or more pore water pressure gauges according to claim 5 are arranged at equal intervals in the face-to-shaft direction at the same height.

7. The setting unit according to any one of claims 5 or 6, which resets the management earth pressure based on the change of the pore water pressure over time.

8. The setting unit according to any one of claims 1 to 4, which resets the management earth pressure based on the following formula (2). (Formula 2) If (Set groundwater pressure - α1) ≦ Pw ≦ (Set groundwater pressure + α2): Do not reset If Pw < (set groundwater pressure - α1) or (set groundwater pressure + α2) < Pw: Reset Here, Pw is the water pressure measured by the pore water pressure gauge, and α1 and α2 are constants. When resetting, the setting unit resets the controlled earth pressure based on the following (Equation 3). (Formula 3) If Pw < (set groundwater pressure - α1): Reduce the set groundwater pressure by β1. If (Set groundwater pressure + α2) < Pw: Increase the set groundwater pressure by β2. Here, β1 and β2 are constants.

9. 8. The earth pressure management system according to claim 5, wherein the setting unit is configured to reset the controlled earth pressure based on the following (Equation 4). (Formula 4) P ｗ１ >P ｗｎ In the case of: Do not reset. P ｗ１ =...= P ｗｎ In the case of: Consider reconfiguration. When to consider resetting: If the pore water pressure gauge reading while shield tunneling is halted gradually decreases over time, do not reset; if it does not change over time, reset. Here, Pwn is the water pressure measured by the pore water pressure gauge, and n is a constant which is set to 1, 2, ..., n in order of proximity to the face. When resetting, the set controlled earth pressure is changed to a value increased by γ1, where γ1 is a constant.

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