JP2010065498A - Box body construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a box body construction method which can install a box body above the existing structure while controlling an influence on the existing structure. <P>SOLUTION: The box body construction method is used for propelling new box bodies 1 in the natural ground M where an underground structure 3 is buried by connecting them to each other one by one. The natural ground surrounding the existing underground structure 3 is excavated in order to install the box body 1, and an assessment value (a floating amount L) is determined based on the displacement of the underground structure 3 incident to the excavation. The assessment value is used for assessing the influence of the excavation of the natural ground M above the underground structure 3 on the underground structure 3. When the assessment value is greater than or equal to a first threshold value, the box body 1 is propelled in a state where a weight 9 used for balancing the earth and sand removed by excavation and the self weight of the box body 1 is installed above the underground structure 3 at least when the box body 1 crosses above the underground structure 3. When the assessment value is smaller than the first threshold value, the box body 1 is propelled without installing the weight 9 at least when the box body 1 crosses above the underground structure 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a box construction method for propelling and installing a new box sequentially connected to a natural ground in which an existing structure is buried.

  If excavation for installing a box is performed above an existing structure such as a tunnel, the load of the removed earth and sand is lost, and the existing structure may float locally. If an existing structure is lifted locally, there is a risk of damage exceeding the allowable stress value at that portion, or the operation of a subway or the like using the structure may be hindered.

Patent Document 1 describes a construction method in which a concrete box is newly constructed while preventing an existing tunnel from being lifted. This method gradually removes the earth and sand above the tunnel as the new concrete box is propelled, and prevents the existing tunnel from being lifted by the weight of the concrete box instead of the removed earth and sand.
JP 2006-214109 A

  However, in the conventional construction method, there is no problem if the earth and sand removed from the ground and the weight of the new box is balanced, but in reality, a box that is so balanced is installed. In rare cases, there was no way to guess whether the earth and sand and the weight of the new box would be balanced, so in practice, while suppressing the effects of lifting of existing structures and stress changes, etc. It was very difficult to construct a new box.

  An object of this invention is to provide the box construction method which can install a box above the existing structure, suppressing the influence on the existing structure.

  The present invention relates to a box construction method for propelling and installing a new box sequentially connected to a natural ground in which an existing structure is buried, and surrounding the existing structure to install the box. Based on the displacement of the structure caused by the excavation, an evaluation value for evaluating the influence on the structure when excavating the natural ground above the structure is obtained. If the threshold is equal to or greater than 1, the weight is installed above the structure to balance the earth and sand removed by excavation and the weight of the box when at least the structure is crossed by the box. If the evaluation value is less than the first threshold, the box is propelled without installing a weight when at least the structure is crossed by the box. .

  When excavating a natural ground around an existing structure, some displacement occurs in the existing structure along with the excavation. This displacement changes according to the soil quality of the ground where the existing structure is buried. If the soil quality of the ground is known, it will be removed when excavating the ground above the structure. The influence on the structure can be evaluated from the relationship between the amount of earth and sand and the displacement described above. In the present invention, by using this relationship, an evaluation value for evaluating the influence on the structure is obtained, and as a result that the evaluation value can be obtained, the weight part for suppressing the influence on the structure, that is, The weight portion for balancing the earth and sand removed by excavation and the weight of the box can be determined. And according to this invention, when the calculated | required evaluation value is more than a 1st threshold value, a box is propelled in the state which installed the weight part above the structure, and an evaluation value is less than a 1st threshold value In this case, since the box is propelled without installing the weight portion, the box can be installed above the existing structure while suppressing the influence on the existing structure.

  Furthermore, it is preferable that the evaluation value is at least one of a lift amount of the structure predicted when excavating a natural ground above the structure and a stress acting on the structure. If a local lift or allowable stress is generated in an existing structure, there is a possibility that the structure is damaged. By adopting the lifting amount as the evaluation value, the box can be installed above the existing structure while accurately suppressing the lifting of the existing structure.

  Furthermore, the box is installed in a semi-underground state after excavating the natural ground, and the box is installed when the evaluation value is less than the first threshold value and the evaluation value is less than the second threshold value. If the evaluation value is less than the first threshold value and the evaluation value is greater than or equal to the second threshold value, excavation for installing the box is preferably performed from the box. is there. When the box is installed in a semi-underground state, if excavation for installing the box can be performed from the ground, workability is improved compared to the case of excavation from the box, and it is safe and quick. Construction becomes possible. However, when excavation is performed from the ground and workability is improved, a large amount of earth and sand is easily removed, and an environment in which an existing structure is easily lifted is created. In other words, by excavating from the ground, the sand around the box is removed, the pressure acting on the existing structure is one of the box's own weight, and the other is the earth pressure that has become lighter as the sand is removed. It occurs, and it becomes a biased state where pressure does not act evenly on the existing structure, and there is a possibility that the structure will be affected by a large bending moment. According to the above method, the second threshold value is defined as a low value that does not affect the existing structure even if excavated from the ground, thereby suppressing the influence on the existing structure. Excavation from the inside and excavation from the box can be performed selectively.

  Further, at least a part of the weight is mounted on the box, and when the evaluation value is equal to or greater than the first threshold, the weight mounted on the box is moved in a direction opposite to the propulsion direction of the box. It is preferable to keep it above the object. Even if the box is installed on a natural ground while propelling the box, the weight portion remains above the existing structure, so that the floating of the existing structure can be continuously suppressed.

  Furthermore, the weight part mounted on the box is composed of a plurality of liquid tanks arranged along the longitudinal direction of the box and the liquid stored in the liquid tank, and the weight part is opposite to the propulsion direction of the box. In order to move, it is preferable to transfer the liquid from one liquid tank in which the liquid is stored to another liquid tank arranged in the direction opposite to the propelling direction of the box. The weight portion can be easily moved, and workability is improved.

  Moreover, when excavating a natural ground for installing the box, it is preferable to form a gradient on the excavation surface in front of the box in the propulsion direction. Comparing the case where the excavated surface is standing upright and the case where a gradient is formed on the excavated surface, assuming that the same amount of earth and sand is removed at once, the former is Disappears all at once, and in the latter case, a small amount of earth and sand remains as much as it forms a gradient. As a result, the former creates an environment that tends to float, and the latter creates an environment that is difficult to lift as much earth and sand remain.

  ADVANTAGE OF THE INVENTION According to this invention, a box can be installed above the existing structure, suppressing the lifting of the existing structure.

  Hereinafter, a preferred embodiment of a box construction method according to the present invention will be described with reference to the drawings.

  As a method of construction while sequentially connecting boxes to the ground and propelling, there are a propulsion method such as the ESA method (ENDRESS SELF ADVANCING METHOD) and a traction method such as the Fronte Jacking Method. In the present embodiment, the ESA method will be specifically described as an example. FIG. 1 is a diagram for explaining each process when constructing a box by the ESA method.

  The ESA method is an abbreviation for “infinite self-propelled forward method”, and is a method in which a box 1 such as a box culvert having a rectangular cross section is constructed in an urban civil engineering structure for a long distance without cutting. In principle, first, the tail is fixed (reaction force) to advance the head, and then the head is fixed (reaction force) to move the tail. This is repeated to advance the box 1 forward.

  As shown in FIG. 1, in the present embodiment, the box 1 is constructed in a semi-underground state on an existing underground structure 3, for example, a natural ground M in which a railway tunnel or the like is embedded. As shown in FIG. 1 (a), shafts H are formed at the start and end of the target natural ground M, and a plurality of (for example, four) boxes 1 are arranged in the shaft H on the start side. The The boxes 1 are connected to each other by PC ore wires, and hydraulic jacks are installed between the boxes 1 and at the rear to constitute an ESA facility.

  Next, as shown in FIG. 1B, each box 1 is advanced in order from the top box 1. When propelling one box 1, the frictional resistance force caused by the earth pressure and the own weight of the other boxes 1 is used as a reaction force resistor, and one box 1 is sequentially propelled one by one. As shown in FIG. 1C, the process continues until the leading box 1 reaches the terminal shaft H and the other box 1 reaches a predetermined position.

  By the way, the underground structure 3 is already embedded in the natural ground M which constructs the box 1. The box 1 is constructed so as to cross the underground structure 3 above the underground structure 3. However, when the earth and sand are discharged, the underground structure 3 may be locally lifted or a stress change may occur. It is necessary to suppress the influence on these underground structures 3. In this embodiment, the evaluation value for evaluating the influence on the underground structure 3 is obtained, and the box 1 is promoted while installing a weight for suppressing the influence on the underground structure 3 based on the obtained evaluation value. I do. Hereinafter, the system and method for suppressing the influence on the underground structure 3 will be described in more detail.

  FIG. 2 is a diagram schematically illustrating the configuration of the vertical load indexing system, and FIG. 3 is a flowchart illustrating a procedure for constructing the box 1 while suppressing the influence on the underground structure 3. As shown in FIG. 2, the existing underground structure 3 is provided with a detection device 5 that detects the amount of vertical displacement of the underground structure 3. The vertical load indexing system receives this detection device 5 and a signal transmitted from the detection device 5 by wire or wirelessly, determines the floating amount (evaluation value) L of the underground structure 3, and further determines the floating amount L. A calculation device 7 is provided for determining the required vertical load W so as to cancel out. The arithmetic device 7 includes a control board on which a CPU, a RAM, a ROM, and the like are mounted, and a display unit 7a such as a liquid crystal monitor. FIG. 2 schematically shows the lift amount L and the required vertical load W that are calculated by the arithmetic unit 7.

  The detection device 5 includes a water sink type subsidence meter. A water sink type subsidence meter is a measuring instrument that detects displacement by connecting a reference water tank and a subsidence meter arranged at each side point with a communicating water pipe and utilizing a phenomenon that the water level at each position becomes constant. Further, the detection device 5 includes a transmitter / receiver, and transmits the displacement detected by the water sink type subsidometer to the arithmetic device 7. The detection device 5 may be provided with, for example, a hydraulic subsidence meter instead of the water-type subsidence meter, and may be provided with other pressure gauges (strain gauges), a displacement gauge, or an inclinometer. Also good.

  The procedure of the box construction method will be described with reference to FIG. When construction of the box 1 by the ESA method is started and a natural ground M around the existing structure is excavated (step S1), some displacement occurs in the underground structure 3 along with the excavation (FIG. 4 (a )reference). The detection device 5 continuously detects the amount of displacement D of the underground structure 3, and the calculation device 7 uses the time when the shaft H is excavated at the start end and the end as a reference, for example, at the reference time. The displacement amount D detected in step 5 is extracted (step S2).

  In this embodiment, the distance between the shafts H is about 50 m to 100 m, and the distance between the shaft H and the underground structure 3 is relatively short, so that some displacement occurs in the underground structure 3 when excavating the shaft H. Therefore, the amount of displacement is extracted when the excavation of the shaft H is performed when the excavation around the underground structure 3 is performed. However, when the distance between the vertical shaft H and the existing structure is very long, and the substantial displacement of the underground structure 3 due to excavation of the vertical shaft H is not expected, it is closer to the underground structure 3 than the vertical shaft H. The timing for excavating the place is preferably set as the timing for extracting the displacement amount D (reference time).

Next, the arithmetic unit 7 calculates the deformation coefficient ε during rebound based on the extracted displacement amount D (step S3). The rebound deformation coefficient ε is a deformation coefficient for determining the displacement of the ground M released from the load of the removed earth and sand when the earth and sand are removed from above the underground structure 3. As for the deformation coefficient ε ₀ when a load is applied to the natural ground M, various compression tests have been widely performed conventionally, and a prescribed value corresponding to the geology is specified in advance. For example, the deformation coefficient is 2,400 (kN / m ² ) when the natural ground M is a loam layer, and the deformation coefficient is 25,700 (kN / m) when it is the first sandy soil layer. m ² ), in the case of the first sedimentary clay layer, the deformation coefficient is set to 15,100 (kN / m ² ) or the like. A small deformation coefficient means that the amount of deformation of the ground is large when a load is applied or when the load is released from the added load. anticipation can be determined by using the value made of, for example, eight times of the deformation coefficient epsilon _0. However, this 8 times is based on the lowest line in consideration of safety and lacks a clear basis, so it is not always accurate. Therefore, in the present embodiment, the deformation coefficient ε at the time of rebound is obtained using a technique called FEM inverse analysis.

  A method using inverse analysis of FEM (Finite Element Method) is a method for determining the deformation coefficient ε at the time of rebound based on the displacement of the underground structure 3 that occurs along with excavation of the natural ground M. The arithmetic unit 7 first creates an FEM model that reproduces the excavation state before excavation of the natural ground M around the underground structure 3, specifically, before excavating the shaft H. The FEM model in this case was subdivided into a plurality of natural ground elements so that the vertical cross section along the propulsion direction F1 in which the box 1 is installed can be subdivided so that the stepwise excavation step of the natural ground M can be considered. This is a model (see FIG. 4B). After the FEM model is created, the arithmetic unit 7 calculates the displacement amount of the underground structure 3 (hereinafter referred to as “displacement amount”) generated by excavation of each shaft H from the sum of the analysis results based on the weight, displacement coefficient, and Poisson's ratio for each mountain element , “Calculated displacement amount”).

Next, the calculation device 7 compares the calculated displacement amount with the displacement amount actually detected by the detection device 5 (hereinafter referred to as “actual displacement amount”), and calculates a more probable value as the displacement coefficient ε during rebound. . The displacement coefficient for determining the calculated displacement amount is based on a value obtained by multiplying the displacement coefficient ε ₀ defined by the properties of the natural ground M by a multiple “8” (hereinafter referred to as “calculated displacement coefficient”). Examining the multiple of the measured displacement coefficient with respect to the displacement coefficient ε ₀ by comparing the calculated displacement coefficient “8 × ε ₀ ” with the displacement coefficient for determining the measured displacement amount (hereinafter referred to as “measured displacement coefficient”). Can do. For example, when the scrutinized multiple is a value of “11.2”, the arithmetic device 7 can calculate “11.2 × ε ₀ ” as the displacement coefficient ε at the time of rebound.

  Returning to FIG. 3, the arithmetic unit 7 obtains an evaluation value for evaluating the influence on the underground structure 3 when the earth and sand above the existing underground structure 3 is removed (step S <b> 4). The evaluation value is obtained based on the displacement coefficient ε at the time of rebound after scrutiny, for example, a predicted value of the lift amount L of the structure, or a predicted value of the stress value (bending moment or axial force) of the tunnel lining Or In the present embodiment, the lift amount L (see FIG. 2) obtained from the load of the earth and sand to be removed and the displacement coefficient ε is used as the evaluation value.

  When the arithmetic unit 7 predicts the lift amount L, the arithmetic device 7 determines whether or not the lift amount L is less than a first specified value (first threshold) (step S5). In the case where the existing underground structure 3 is a tunnel such as a subway, an allowable value of the lifting amount L is determined by an operation rule or the like, for example, about 8 mm is allowed. In the present embodiment, for example, 8 mm is set as the first specified value, and when the predicted lift amount L is less than 8 mm, the calculation device 7 compares the second specified value described later. If it is 8 mm or more, the required vertical load W is calculated without comparing with the second specified value. In addition, when employ | adopting the predicted value of the stress value which acts on tunnel lining as an evaluation value, the allowable stress of tunnel lining etc. can be employ | adopted for a 1st specified value (1st threshold value). .

  The required vertical load (see FIG. 2) W intends the total load amount and the load acting range that are necessary for balancing the earth and sand to be removed and the weight of the box 1. When calculating the total load amount and the load action range, the arithmetic device 7 displays the total load amount and the load action range on the display unit 7a so that the operator can visually recognize the load amount and the load action range.

  Next, the operator selects a weight (weight part) 9 based on the total load of the necessary vertical load W displayed on the display unit 7a, and further, based on the load acting range displayed on the display unit 7a, A weight 9 is installed on the tip of the box 1 or on the ground (see FIG. 5A). The weight 9 can be obtained by storing water in a plastic container such as a plastic tank. The weight 9 is stored in a plurality of containers so that the total amount of the load is reached, and the containers are placed within the load action range. Installation is completed.

  Next, the operator uses a heavy machine 10 such as a backhoe to excavate the natural ground M from the inside of the box 1, and advances the box 1 while discharging the excavated earth and sand (see FIG. 5B). . In this case, the operator propels the box 1 with the weight 9 for balancing the earth and sand removed by excavation and the weight of the box 1 above the underground structure 3, and the underground structure 3 Cross the top of. The excavated earth and sand are discharged to the start side shaft H by a belt conveyor and discharged.

  Further, as the box 1 is propelled, the operator moves the weight 9 mounted on the box 1 in a direction F2 opposite to the propelling direction F1 of the box 1 so as to keep it above the structure. Yes. Therefore, even if the weight 9 is installed on the natural ground M while propelling the box 1, the weight 9 remains above the existing underground structure 3, so that the floating of the existing underground structure 3 can be continuously suppressed.

  As shown in FIG. 3, when it is determined that the predicted lift amount L is less than the first specified value (step S5), the arithmetic unit 7 determines that the predicted lift amount L is the second specified value. It is determined whether it is less than (second threshold value) (step S8). In the present embodiment, the second specified value is specified as 70% of the first specified value. For example, the second specified value is specified as 5.6 mm. When the predicted value of the stress value acting on the tunnel lining is adopted as the evaluation value, the second specified value (second threshold) is the first specified value such as the allowable stress of the tunnel lining. It can be set to 70% of (the first threshold).

  The second specified value is a reference for determining whether excavation of the natural ground M is performed from the inside of the box 1 or outside the box 1. When the box 1 is installed in a semi-underground state, if excavation for installing the box 1 can be performed from the ground, workability is improved as compared to the case of excavation from the inside of the box 1, Safe and quick construction is possible. However, when excavation is performed from the ground and workability is improved, a large amount of earth and sand is easily removed, and an environment in which the existing underground structure 3 is easily lifted is created. That is, the earth and sand around the box 1 is removed by excavating from the ground, and the pressure acting on the upper part of the underground structure 3 is one of the dead weight of the box 1 and the other is the earth pressure that becomes lighter as the sand is removed. As a result, an unbalanced state in which no pressure acts evenly on the underground structure 3 may occur, and the underground structure 3 may be affected by a large bending moment or the like. Therefore, even if excavation from the ground, by setting the second specified value to a low value that does not affect the lift or bending moment, the lift of the existing underground structure 3 is suppressed from the ground. Excavation and excavation from the box 1 can be performed selectively.

  If the calculation device 7 determines that the predicted lifting amount L is less than the second specified value as a result of the determination in step S8, the operator displays a message indicating that the weight 9 is not required to be installed. It displays on the display part 7a so that it can visually recognize. Furthermore, the arithmetic unit 7 displays a message indicating that excavation from the ground is possible on the display unit 7a so that the operator can visually recognize the message.

  An operator who has confirmed the message displayed on the display unit 7a uses a heavy machine 10 such as a backhoe to excavate the natural ground M from the ground outside the box 1 and discharge the excavated earth and sand. Is moved forward (see FIG. 6B). In this case, the operator propels the box 1 without installing the weight 9 and crosses the upper part of the underground structure 3. And when installing the box 1 in a semi-underground state, excavating the natural ground M from the outside of the box 1 makes it unnecessary to carry in the heavy machine 10 into the box 1 and discharges excavated earth and sand. Etc., and the workability is greatly improved. Furthermore, safety can be expected to improve as work efficiency improves.

  In particular, in this embodiment, in excavation from the ground, a gradient is formed on the excavation surface M1 in front of the box 1 in the propulsion direction F1. This gradient is a shape in which the lower end in the vertical direction is close to the box 1 and the upper end is separated from the box 1 and the excavated hole is expanded on the upper side. The angle θ of the gradient with respect to the horizontal plane can be appropriately selected according to the depth of the hole and the nature of the natural ground M. For example, when the natural ground M is made of rock or hard soil, it is about 75 °. In some cases, the angle can be about 60 °. Comparing the case where the excavation surface M1 rises vertically and the case where the excavation surface M1 has a gradient, assuming that the same amount of earth and sand is removed at once, the former shows that the earth and sand vertically above the existing underground structure 3 is It disappears all at once, and in the latter case, a slight amount of earth and sand remains as much as it forms a gradient. As a result, the former creates an environment that tends to float, and the latter creates an environment that is difficult to lift as much earth and sand remain.

  As a result of the determination in step S8, the arithmetic unit 7 determines that the predicted lift amount L is greater than or equal to the second specified value, and the operator receives a message indicating that the weight 9 is not required to be installed. It displays on the display part 7a so that it can visually recognize. Furthermore, the arithmetic unit 7 displays a message indicating that excavation from the ground is impossible and excavation from the inside of the box 1 is possible on the display unit 7a so that the operator can visually recognize the message.

  An operator who has confirmed the message displayed on the display unit 7a uses a heavy machine 10 such as a backhoe to excavate the ground M from the inside of the box 1 and advance the box 1 while discharging the excavated earth and sand. (See FIG. 8 (a)). In this case, the operator pushes the box 1 without installing the weight 9 and crosses the upper part of the underground structure 3. And since excavation is performed from the inside of the box 1, the weight of the box 1 is increased by the amount of the heavy machine 10, and the floating of the underground structure 3 can be effectively suppressed during excavation.

  The operation and effect of the box construction method according to the present embodiment will be described. When excavating the natural ground M around the existing underground structure 3, some displacement occurs in the existing underground structure 3 along with the excavation. This displacement changes according to the properties of the natural ground M in which the existing underground structure 3 is buried. If the properties of the natural ground M can be grasped, the natural ground M above the underground structure 3 is understood. From the relationship between the amount of earth and sand removed when excavating and the above-mentioned displacement, the influence on the underground structure 3, for example, the lift amount L can be predicted. In the box construction method according to the present embodiment, the lift amount L is predicted by using this relationship, and as a result of predicting the lift amount L, the weight 9 for suppressing the lift amount L, that is, by excavation The weight 9 for balancing the earth and sand to be removed and the weight of the box 1 is determined. When the predicted lifting amount L is equal to or greater than the first specified value, the box 1 is propelled with the weight 9 installed above the structure, and the lifting amount L is less than the first specified value. In the case, the box 1 is propelled without installing the weight 9. As a result, while suppressing the floating of the existing underground structure 3, the new box 1 can be propelled while being sequentially connected above the existing underground structure 3.

  Further, the box 1 is installed in a semi-underground state after excavating the natural ground M, and the predicted lift amount L is less than the first specified value and the lift amount L is less than the second specified value. When the excavation for installing the box 1 is performed from the ground, the lift amount L is less than the first specified value, and the lift amount L is equal to or greater than the second specified value, the box 1 The excavation for installing is carried out from inside the box 1. Since the second specified value is set to a low value that does not affect the lift even if excavated from the ground, excavation from the ground and the box 1 Can be selectively performed.

(Second Embodiment)
Next, the box construction method according to the second embodiment will be described with reference to FIG. Fig.7 (a) is a figure which shows typically the state just before the box 1 crosses the upper direction of the existing underground structure 3, FIG.7 (b) is a box from the state of Fig.7 (a). It is a figure which shows typically the state after progress of 1 progressed, and the box 1 was installed so that the upper direction of the existing underground structure 3 might be crossed.

  In the box construction method according to the present embodiment, the work associated with the installation of the weight 9 shown in step S7 is different from the construction procedure shown in FIG. 3 as compared to the first embodiment. In the present embodiment, a plurality of water tanks (liquid tanks) 11, 13, and 15 are installed in the inside of the box 1, the upper surface of the box 1, and the ground surface above the underground structure 3. The water tanks 11 inside the box 1 are arranged side by side along the longitudinal direction of the box 1, and the water tanks 13 above the box 1 are arranged side by side along the longitudinal direction of the box 1. Yes. In addition, the water tanks 15 installed on the ground surface are arranged side by side on the course promoted by the box 1. As the water tanks 11, 13, and 15, resin containers that can be removed as appropriate can be used, and the water tanks 11, 13, and 15 in a state where water is stored correspond to weight parts. It should be noted that the liquid stored in the water tanks 11, 13, and 15 may be other liquids that are easy to handle and safe instead of water.

  When calculating the total load amount and the load action range as the required vertical load W, the arithmetic device 7 displays the total load amount and the load action range on the display unit 7a so that the operator can visually recognize the load amount. Here, the information displayed on the display unit 7a includes, for example, the water tanks 13 and 15 for storing water among the plurality of water tanks 11, 13, and 15 installed in the box 1, the upper part, or the ground surface. This is information about the number, arrangement, or amount of water stored.

  Next, the operator selects the water tanks 11, 13, and 15 based on the total load displayed on the display unit 7a, and stores water in the selected water tanks 11, 13, and 15. Thereafter, the operator uses a heavy machine 10 such as a backhoe to excavate the natural ground M from the inside of the box 1 and advances the box 1 while discharging the excavated earth and sand.

  Here, the water tanks 11 and 13 are also moved following the promotion of the box 1, and when the water tanks 11 and 13 are moved, the water tanks 11 and 13 in which water is stored are out of the load acting range. Therefore, the worker uses a hose or a pump, for example, to transfer water from one water tank 11 to another water tank 11 arranged in the direction F2 opposite to the propelling direction F1 of the box 1 to store the water. 11 and 13 are prevented from deviating from the load acting range. As a result, even if the box 1 is propelled and installed in the natural ground M, the water tanks 11 and 13 in which the water is stored remain above the existing underground structure 3, so that the existing underground structure 3 is lifted. Can be suppressed continuously. In order to keep the water tanks 11 and 13 in which water is stored above the underground structure 3, basically, the center of gravity of the load as the weight portion is set in the direction F2 opposite to the propulsion direction F1 of the box 1. It is necessary to shift towards. However, the present invention is not limited to such movement of the center of gravity. For example, when the box 1 is propelled, the center of gravity needs to be shifted in order to balance the earth and sand removed and the weight of the box 1. May transfer water in the forward direction of the propelling direction F1 of the box 1.

  Similarly to the box construction method according to the first embodiment, when the predicted lifting amount L is equal to or greater than the first specified value, the box construction method according to the present embodiment is used to set the weight 9 above the structure. When the box 1 is propelled in the state where it is installed and the lifting amount L is less than the first specified value, the box 1 is propelled without installing its weight 9, so that the existing underground structure 3 The box 1 can be installed above the existing underground structure 3 while suppressing the lifting.

  In particular, in this embodiment, water tanks 11, 13, and 15 storing water are used as weight parts for balancing the earth and sand removed by excavation and the weight of the box 1, and the water tanks 11 and 13 are used. It is mounted on the box 1. Then, the water tanks 11 and 13 in which water is stored by moving the water in the direction F2 opposite to the propelling direction F1 of the box 1 are kept above the underground structure 3. As a result, even if it is installed in the natural ground M while propelling the box 1, the water tanks 11 and 13 in which water is stored remain above the existing underground structure 3, so that the existing underground structure 3 is lifted. In addition, the center of gravity of the load as the weight portion can be easily moved by the transfer of water, and workability is improved.

  The present invention is not limited to the above embodiments. For example, in each of the above-described embodiments, the propulsion method for constructing the box by the EMS method has been described as an example. However, the box by the traction method such as the front jacking method or the combination of the propulsion method and the traction method. It may be a construction method of installing. By the way, the Fronte Jacking (FJ) method is a construction method in which the box is embedded in a non-open cut or installed in a semi-underground state, and a PC steel wire is used between the reaction body on the arrival side and the casing on the transmission side. It is a method of connecting and using a center hole jack (front jack) to pull (promote) the box to a predetermined position.

It is a typical process diagram for explaining the process of the EMS propulsion method according to the embodiment of the present invention. It is a figure which shows a vertical load indexing system typically. It is a flowchart which shows the operation | movement procedure of the construction method which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the reverse analysis of FEM, (a) is a figure which shows the displacement of the existing underground structure, (b) is a figure which shows a FEM model typically. It is a figure for demonstrating the case where a weight is installed and constructing a box, (a) is a figure showing the state where a weight was installed above an underground structure, and (b) is a box. It is a figure which shows typically the state excavated from the inside. It is a figure for demonstrating the case where a box is constructed without installing a weight, (a) is a figure showing typically the state where it excavates from the inside of a box, and (b) is from the ground. It is a figure which shows typically the state which is excavating. It is a figure for demonstrating the case where a part of water tank is installed in a box, and water is stored in a water tank and a box is constructed according to 2nd Embodiment of this invention, (a) is a box. It is a figure which shows typically the state just before crossing the upper part of an underground structure, (b) is a state which propelled a box so that it crosses an underground structure, and the state in which the water in a water tank is transferred FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Box, 3 ... Underground structure (structure), 5 ... Detection apparatus, 7 ... Calculation apparatus, 9 ... Weight, 11, 13 ... Water tank (liquid tank), F1 ... Propulsion direction of box, F2 ... Box Reverse direction of body propulsion direction, M ... natural ground, M1 ... cutting surface.

Claims (6)

In a box construction method for propelling and installing a new box in order to connect to a natural ground where an existing structure is buried,
Excavating natural ground around the existing structure to install the box,
Based on the displacement of the structure caused by the excavation, an evaluation value for evaluating the influence on the structure when excavating a natural ground above the structure is obtained,
When the evaluation value is equal to or greater than the first threshold value, the weight portion for balancing the earth and sand removed by excavation and the weight of the box at least when the box is crossed over the structure is the weight. Promote the box in the state of being installed above the structure,
When the evaluation value is less than the first threshold value, the box is propelled without installing the weight part when at least the structure is crossed by the box. Construction method.   2. The evaluation value according to claim 1, wherein the evaluation value is at least one of a lift amount of the structure predicted when excavating a natural ground above the structure and a stress acting on the structure. Box body construction method. The box is installed in a semi-underground state after excavating the natural ground,
When the evaluation value is less than the first threshold value and the evaluation value is less than the second threshold value, excavation for installing the box is performed from the ground,
The excavation for installing the box is performed from the box when the evaluation value is less than a first threshold value and the evaluation value is not less than the second threshold value. Item 1 or 2 box construction method. At least a part of the weight is mounted on the box,
When the evaluation value is equal to or greater than the first threshold value, the weight portion mounted on the box is moved in the direction opposite to the propulsion direction of the box and is held above the structure. The box construction method as described in any one of Claims 1-3. The weight portion mounted on the box is composed of a plurality of liquid tanks arranged along the longitudinal direction of the box, and a liquid stored in the liquid tank,
In order to move the weight part in a direction opposite to the propelling direction of the box, the liquid is transferred from one liquid tank in which the liquid is stored to another liquid tank arranged in the direction opposite to the propelling direction of the box. The box construction method according to claim 4, wherein the box is transferred.   The box construction method according to claim 3, wherein when excavating a natural ground for installing the box, a slope is formed on a drilling surface in front of the box in the propulsion direction.

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