JP5204063B2 - Box foundation construction method in open shield method - Google Patents

Description

  The present invention relates to a method for building a box foundation in an open shield method using an open shield machine for constructing underground structures such as an attached underground passage such as a water and sewage system, a common ditch, a telegraph and a telephone.

  The open shield method is a highly rational method that utilizes the advantages of the open cut method (open cut method) and the shield method. FIG. 3 schematically shows an open shield machine 1 in the figure, which is a shield machine having front, rear and top surfaces each including left and right side wall plates 1a and a bottom plate 1b connected to the side wall plates 1a. It is.

  In this open shield machine 1, the front ends of the side wall plate 1a and the bottom plate 1b are formed as blade edges 11, and the propulsion jacks 2 are arranged in the vertical direction in the center or near the rear end of the side wall plate 1a. In the figure, 3 indicates a partition wall.

  The open shield method to be constructed using such an open shield machine 1 is not shown in the figure, but this open shield machine 1 is installed in the start pit, and the propulsion jack 2 of the open shield machine 1 is extended so that the The open shield machine 1 is moved forward with the reaction force against the reaction wall, the first concrete box 4 forming the underground structure is suspended from above, and the propulsion is shrunk in the tail portion 1c of the open shield machine 1 Set behind jack 2. A strut is disposed between the propulsion jack 2 and the reaction wall to adjust the distance appropriately.

  In addition, the start pit is made up of a retaining wall, and in order to start the open shield machine 1, a part of this retaining wall is mirror-cut. If necessary, the ground is improved at the front part of the starting pit by chemical injection or the like. Sometimes it is left.

  Excavator 9 such as an excavator excavates and removes soil from the front or top surface of open shield machine 1. At the same time as or after this earth removal step, the propulsion jack 2 is extended to advance the open shield machine 1. In the case of this forward process, a pushing angle 8 made of a frame made of box steel or mold steel is arranged in front of the concrete box 4, and the open shield machine 1 receives a reaction force from the concrete box 4 set rearward. Take.

  Then, the second concrete box 4 is suspended in the tail portion 1 of the open shield machine 1 in front of the first concrete box 4. Thereafter, the same soil removal process, advance process, and setting process of the concrete box 4 are repeated as appropriate, and the concrete boxes 4 are sequentially left in the ground in line with the advancement of the open shield machine 1, and further this concrete box. Put backfill 5 on the upper surface of 4.

  When the concrete box 4 is suspended in the tail part 1c of the open shield machine 1, a height adjusting material 7 such as a concrete block is disposed under the concrete box 4, and the concrete part 4 is placed in the tail part 1c. The grout material 6 is filled in the left and right and lower spaces of the box 4.

  In this way, if the open shield machine 1 reaches the reaching mine, it is removed and the construction is completed.

  In such an open shield construction method, as described above, the concrete box 4 is left in the ground in a column as the open shield machine 1 advances, and the concrete box 4 is suspended in the tail portion 1c of the open shield machine 1. As the open shield machine 1 moves forward, it leaves the tail portion 1c and remains in the ground. The open shield machine 1 takes a reaction force on the concrete box 4 left in the ground in this way. Advance.

  The concrete box 4 is made of reinforced concrete. As shown in FIG. 4, the concrete box 4 is an integrated body including a left side plate 4 a, a right side plate 4 b, an upper floor plate 4 c and a lower floor plate 4 d, and the front and rear surfaces are opened as openings 10.

  By the way, when the laying place of the concrete box 4 is soft ground, if there is a corrosive soil layer or ultra-soft layer between the supporting ground and the box, there is a risk of settlement due to consolidation of the laid concrete box. is there.

  Therefore, as a means for avoiding such inconvenience, when filling the backfilling material around the concrete box in the open shield method, a method of replacing the entire soft ground portion with the backfilling material can be considered.

  On the other hand, when laying a concrete box by the open-cut method, a replacement work with a crushed stone foundation 16 is performed on the corrosive soil layer or the soft ground 15 directly below the concrete box 4 as shown in FIG. 5, and as shown in FIG. The ground improvement work 17 is performed.

  However, the settlement prevention method in the case of the above-mentioned excavation method requires excavation of the inside of the retaining wall 18 up to the replacement portion by the crushed stone in the case of the crushed stone foundation 16 shown in FIG. become longer.

  As a result, when a nearby structure such as a house is present at the construction site, the influence on the nearby structure due to the earth retaining pulling is increased, which may disturb the replacement work by the crushed stone.

  In addition, when a foundation made of crushed stone is built under a condition where the groundwater level is high, since the gap between the built crushed stone foundation 16 is large and the hydraulic conductivity is high, excess pore water pressure generated during an earthquake acts on each crushed stone, and the crushed stone foundation 16 Is prone to disturbance.

  In addition, in the case of the ground improvement work 17 shown in FIG. 6, the passive earth pressure inside the retaining wall 18 can be achieved by the ground improvement, and the installation of the retaining wall 18 can be minimized, but the construction cost and the construction days required for the ground improvement are reduced. Increased and uneconomical.

  The prior art is generally performed by those skilled in the art, and does not relate to a known literature invention.

  When laying a concrete box with the open shield method, there is no inconvenience as in the open cut method, but with the method of replacing the entire soft ground part only with the backfilling material, the backfilling material thickness increases, It becomes uneconomical.

  The object of the present invention is to eliminate the inconvenience of the conventional example, and when laying a concrete box by the open shield method, it is safe and has little influence on the surroundings, and the box foundation in a series of steps of the open shield method. It provides a method for building a box foundation in the open shield method with little foundation disturbance.

In order to achieve the above object, the invention according to claim 1 includes a step of excavating and discharging soil in front of an open shield machine or a front opening of the open shield machine, and extending a propulsion jack to depress the concrete box. Open shield construction method in which concrete boxes are sequentially embedded in columns by repeating the process of moving the shield machine forward with force and the process of setting a new concrete box behind the propulsion jack shrunk in the tail of the shield machine. In the open shield machine, the length of the left and right side wall plates reaches the lower end of the soft ground layer, the bottom plate is provided at the lower end of the left and right side wall plates, and the bottom plate is placed at the lower end of the soft ground layer. disposed at a height position to reach, drilling ground deeply concrete box-body below the installation depth of the concrete box-body, open shield machine 1 concrete box making body min After excavation, this excavated part is ground improved with basic crushed stone and backfilling injection material, and a box composed of multiple layers of layers filled with backfilling injection material in the crushed stone layer below the planned location of the concrete box. The gist is to build a body foundation, and this box foundation is integrated with the back-filling material injected into the side of the concrete box.

  According to the first aspect of the present invention, since the bottom plate of the open shield machine reaches the lower end of the soft ground layer, excavation and soil removal of the soil in front of the open shield machine is performed in a series of steps of the open shield construction method. In this process, the soft ground below the concrete box to be laid can be excavated, and the box foundation can be built in this part, so the construction days can be shortened compared to the open-cut method.

  In addition, since the box foundation is built by filling the gap between the basic crushed stones with the backfill injection material, the backfill injection material filled into the gap between the crushed stones solidifies and develops strength, and the water permeability is also reduced. There is almost no disturbance of the foundation built by the excess pore water pressure generated at the time of the earthquake compared to the foundation made of crushed stone alone.

  Furthermore, it is more economical than the case where the box foundation is constructed only with the backfilling material.

  In addition to this, the box foundation is composed of a plurality of layers of layers in which the crushed stone layer is filled with the backfilling injection material, so that the backfilling injection material is reliably filled in the crevice stones and can exhibit strength. .

  In addition, the box foundation is integrated with the backfilling material injected into the side of the concrete box, the gap between the basic crushed stones just below the box is filled with backfilling material, and the side of the box is also backfilling injection material Because it is filled with water, it can be safely and even on the ground with high groundwater level, and there is almost no impact on the surroundings, and it can be replaced with soft ground by backfilling material and crushed stone foundation, and the box is laid easily and reliably it can.

  As described above, the method of building the box foundation in the open shield method of the present invention, when laying the concrete box by the open shield method, because the backfilling material was filled in the gap between the crushed stone foundation, By solidifying the backfilling material, strength can be expressed, there is almost no disturbance of the foundation, it is safe, there is almost no influence from the surroundings, and in the drilling and earth removal process in the series of processes of the open shield method A box foundation can be constructed, and construction days can be shortened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal side view showing an embodiment of a box foundation construction method in the open shield construction method of the present invention, FIG. 2 is a longitudinal front view of a box laying portion same as above, and the basic structure of the open shield machine 1 of the present invention is also shown in FIG. It is the same as that of the prior art shown in FIG. 3, and the same reference numerals are assigned to the same components.

  The structure of the open shield machine used in the present invention will be described. Assuming the case of excavating the soft ground, the length of the left and right side wall plates 1a of the open shield machine 1 is set to a length that reaches the lower end of the soft ground layer as shown in FIGS. A bottom plate 1b is provided at the lower ends of the left and right side wall plates 1a. Thereby, the baseplate 1b will be located in the lower end of a soft ground layer.

  A method for laying the concrete box 4 using the open shield machine 1 in which the bottom plate 1b is disposed at a height position that reaches the lower end of the soft ground layer will be described. Excavation and soil removal in front of the open shield machine 1 in the same manner as the conventional open shield method, and the reaction force is applied to the concrete box 4 at the back to make the open shield machine 1 one box of the concrete box 4. Dig up.

  The excavation of the earth and sand at this time excavates not only the height of the concrete box 4 to be laid but also the depth to the bottom plate 1b of the open shield machine 1. Therefore, the soft ground layer below the concrete box 4 to be laid is also excavated.

  If the open shield machine 1 is dug and a space for laying the concrete box 4 in the tail part 1c is secured, below the laying space of the concrete box 4, several layers of single-grain crushed stone in the tail part 1c are formed. Separately spread and level, and fill the gap between single leveled crushed stones with the back-filling material for each layer.

  In this way, if the box foundation 12 is built up to a predetermined height, that is, a height position where the concrete box 4 is laid, by crushing the crushed stone and filling the backfill material, the box foundation 12 Set the concrete box 4 on top.

  Since the box foundation 12 constructed directly under the concrete box 4 is filled with the backfilling material in the gap between the crushed stones spread as described above, the whole foundation is solidified by this backfilling material, There is no turbulence in the built-up box foundation.

  And, the backfilling material filled in the gap between the crushed stones is solidified, and the strength is developed, and the permeability of the foundation is reduced, and the foundation constructed by the excess pore water pressure generated at the time of the earthquake is hardly disturbed. .

  After the concrete box 4 is set on the box foundation 12, the backfilling material is also filled in the gap between the side wall of the concrete box 4 and the side of the tail part 1 c of the open shield machine 1.

  Then, the open shield machine 1 is dug. Then, the back injection material 13 is filled into the tail void generated by the excavation from the grout hole previously set in the concrete box 4. As a result, the back injection material is filled directly below and on the side of the concrete box 4, and the back injection material filled in both places is united. For example, even in the ground with a high groundwater level, There is almost no influence on the surroundings, and the replacement foundation made of backfilling material and foundation crushed stone is built on the soft ground, making it easy to construct 4 concrete boxes.

  Since the construction of the box foundation 12 can be performed by incorporating it into the process as a part of a series of processes of the open shield construction method, the construction days can be shortened compared to the case of building the box foundation by the open-cut construction method, The number of construction days and costs can be reduced even when the ground is improved only with the backfilling material.

It is a vertical side view which shows embodiment of the construction method of the box foundation in the open shield method of this invention. It is a vertical front view which shows embodiment of the construction method of the box foundation in the open shield method of this invention. It is a vertical side view which shows the outline of an open shield construction method. It is a perspective view of a concrete box. It is a vertical front view which shows the 1st example of the construction method of the box foundation by the open-cut method. It is a vertical front view which shows the 2nd example of the construction method of the box foundation by the open-cut method.

DESCRIPTION OF SYMBOLS 1 Open shield machine 1a Side wall plate 1b Bottom plate 1c Tail part 2 Propulsion jack 3 Bulkhead 4 Concrete box 4a Left side plate 4b Right side plate 4c Upper floor plate 4d Lower floor plate 5 Backfill soil 6 Grout material 7 Height adjustment material 8 Pushing angle 9 Excavator DESCRIPTION OF SYMBOLS 10 Opening 11 Blade edge 12 Box foundation 13 Backfilling material 15 Soft ground 16 Crushed stone foundation 17 Ground improvement work 18 Earth retaining wall

Claims (1)

The process of excavating and discharging soil in front of the front or top opening of the open shield machine, the process of extending the propulsion jack and advancing the shield machine with the concrete box as a reaction force, and shrinking in the tail part of the shield machine In the open shield method in which the concrete box is buried in series in sequence by repeating the process of setting a new concrete box behind the propulsion jack, the open shield machine uses the length of the left and right side walls as the soft ground layer. The bottom plate is provided at the lower end of the left and right side wall plates, and the bottom plate is disposed at a height that reaches the lower end of the soft ground layer, deeper than the installation depth of the concrete box. After excavating the ground below the concrete box and the open shield machine excavates by one concrete box, this excavated part is covered with basic crushed stone and backfilling material. A box foundation composed of multiple layers of crushed stone layers filled with back-filling injection material is built below the place where the concrete box is planned to be laid, and this box foundation is injected into the side of the concrete box. The box foundation construction method in the open shield construction method, characterized by being integrated with the backfill injection material.

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