JP2014129690A - Hydraulic pressure suppression method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an efficient decrease in water-level within a desired range with good workability.SOLUTION: A hole 110 linking the inside and outside of an underground structure such as an underground part 12 of an existing structure 10 to each other is formed in a region, for example, a floor slab 13 contacting underground water 5, of the underground part 12, and negative pressure is applied to the hole 110 by a vacuum pump 120 so as to make underground water 5 outside the underground structure flow into an underground space 15.

Description

  The present invention relates to a water pressure suppression method, and specifically relates to a technique for realizing efficient water level reduction in a desired range with good workability.

  From the viewpoints of environmental considerations such as resource saving, construction cost reduction, and response to narrow construction areas, there is a construction need to dismantle the ground part of existing structures and reuse only the underground part. If such construction is performed on a structure in which pressurized groundwater acts on the underground part, the weight of the structure after removal of the ground part and the water pressure acting on the structure will not be balanced, and this will correspond to the underground part of the structure. Excessive stress may act on the floor slab and side walls, and it may cause lifting. The following techniques have been proposed as a technique for coping with such problems such as structural damage and floating caused by groundwater pressure.

  That is, in the underground structure, a hole penetrating from the bottom of the floor slab to the interior of the underground structure is provided, and the groundwater level that is directly below the floor slab is guided by guiding the groundwater that self-injects through the hole to the interior of the underground structure. There has been proposed a drainage device (see Patent Document 1) or the like that lowers water. In addition, water collection points, that is, well points, are installed at predetermined intervals on the ground around the underground structure, and a suction operation is performed by a vacuum pump through a pipe connecting the well points, and groundwater is pumped up to surround the underground structure. Conventionally, a well point technique for lowering the groundwater level has also been proposed.

JP-A-11-303115

  As in the prior art, when adopting a method to take in groundwater that is self-jetting under pressure through a hole formed in the floor slab, the depth at which the groundwater level can be lowered is up to directly below the floor slab where the hole is located, The groundwater level cannot be lowered further. Moreover, the area where the groundwater level can be lowered to just below the floor slab is only in the vicinity of the hole. Therefore, depending on the specifications of the target underground structure, there is a concern that the effects of damage and floating due to groundwater pressure cannot be avoided. In addition, if the diameter of the above-mentioned hole is enlarged in order to sufficiently reduce the groundwater level by guiding a lot of groundwater, the decrease in strength around the relevant part of the floor slab also increases, increasing the labor and cost of subsequent repair work, etc. To do. In addition, large-scale equipment is required to form a large-diameter hole, and there are problems in terms of carrying in equipment in a limited underground space and securing a construction area.

  On the other hand, when the well point method is adopted, forced pumping is performed from the outside of the water blocking wall using a vacuum pump, so the amount of pumping tends to increase, and the groundwater level around the underground structure is unnecessarily lowered. There is also a risk of letting you. Furthermore, when constructing the well point method, it is necessary to introduce a series of systems in which a large number of pipes leading to the well point in the ground are arranged in parallel and connected to large-scale pumps for sucking them. However, it is difficult to apply to small urban areas.

  Therefore, an object of the present invention is to provide a technique for realizing efficient water level reduction within a desired range with good workability.

  The water pressure suppression method of the present invention that solves the above problems is to form a hole communicating with the inside and outside of the underground structure in a portion in contact with the ground water in the underground structure, and apply a negative pressure to the hole with a vacuum pump to It is characterized in that groundwater outside the object flows into the underground structure. According to this structure, the desired drainage work can be performed with a simple and small-scale equipment configuration consisting of a small-diameter hole provided in the floor slab or side wall of the structure and a vacuum pump, and the construction space is likely to be limited. Good workability can be achieved even for objects.

  Further, in addition to the groundwater that is spontaneously jetted from the hole into the underground structure, the groundwater that is sucked into the underground structure by the negative pressure derived from the vacuum pump applied to the hole is also drained. Therefore, the water level is not lowered only in a very narrow range directly under the floor slab, but it is drawn from the floor slab directly to the groundwater at an appropriate depth according to the magnitude of the negative pressure (vacuum level) generated by the vacuum pump. As a result, it is possible to drain the appropriate range of groundwater.

  Therefore, it becomes possible to drain groundwater in a desired range by adjusting the negative pressure generated by the vacuum pump, and thus the water pressure applied to the underground structure can be reliably and efficiently suppressed. By controlling the vacuum pump in this way and efficiently suppressing water pressure with respect to the target underground structure, it is possible to avoid a situation where unnecessary groundwater level drop occurs in the surrounding environment.

  Moreover, the above-mentioned hole provided in the floor slab and the side wall and the vacuum pump arranged around the hole are located at substantially the same depth as the groundwater level in the ground. In that case, the negative pressure generated by the vacuum pump is a large loss. Without emptying the inside of the hole, drainage is efficiently performed. Therefore, unlike the well point method, there is no problem that the negative pressure is lost because the suction operation is performed over a long distance from the ground surface, and efficient drainage and thus the water pressure is not suppressed.

  Therefore, according to the present invention, it is possible to achieve efficient water level reduction within a desired range with good workability.

  In the water pressure suppression method described above, the well from the hole to the formation at a predetermined depth is drilled, the negative pressure is applied to the hole by a vacuum pump, and the groundwater outside the underground structure collected through the well is subsurface. It may be allowed to flow into the interior. According to this, by using a small-diameter self-injection well (for example, a relief well) that reaches a depth corresponding to the required groundwater level drop and a vacuum pump, efficient water collection from the aquifer through the well is achieved. At the same time, negative pressure can be applied to the well through the hole to further increase the water collection capacity of the well, thereby efficiently draining water and suppressing water pressure.

  Further, in the above-described water pressure suppression method, the pipe connected to the above-mentioned hole is connected to the inner space of the predetermined container, and the inner space of the predetermined container is decompressed with a vacuum pump, thereby collecting water through the hole or the well. The groundwater outside the underground structure may be discharged into a predetermined container, and the groundwater discharged into the predetermined container may be drained with a submersible pump. According to this, the negative pressure generated by the vacuum pump can be applied to a container having a larger volume than the small-diameter hole, and the fluctuation of the negative pressure applied to the hole via this container can be reduced and stabilized. Therefore, the amount of groundwater pumped from the underground through the hole is also stabilized.

  Further, in the above-described water pressure suppression method, the inside of the predetermined container is partitioned by a dam plate, a pipe is connected to the first partition, the ground water is discharged, and the ground water flows into the second partition after overflowing the dam plate from the partition. It is good also as draining with a submersible pump. According to this, the groundwater discharged | emitted in the container is stored in the division which uses a dam plate as a boundary, and only the part which filled the inside of a division and overflowed from the dam plate will be drained to the ground surface. Therefore, the water surface is kept constant in the section where the pipe is guided, the volume of the container inner space is also constant, and a negative pressure can be stably applied to the container inner space. Therefore, the amount of groundwater to be pumped is also stabilized.

  Further, in the above-described water pressure suppression method, the first compartment in the predetermined container is divided into a plurality of sections, pipes are connected to the sections, and groundwater is caused to flow from each pipe into the corresponding section to which the pipe is connected. The groundwater that has overflowed the dam plate from each section and has flowed into the second section common to the first section may be drained by a submersible pump. According to this, groundwater collected from a plurality of holes or wells is guided to each section (first divided section) in the container through each pipe, stored in each section, and filled with groundwater. Only the groundwater that overflows from the section above the weir plate is collected in the second section (one section shared by each pipe) in the container and drained to the surface by the submersible pump placed in this section. It will be. Therefore, in each section where the piping of each hole or well is led, even if there is a difference in the water collection speed for each hole or well, the water surface is kept constant, the volume of the container empty space is also constant, Negative pressure can be stably applied to the sky. Therefore, the amount of groundwater collected from a plurality of holes and wells and pumped to the ground surface can be easily stabilized.

  According to the present invention, it is possible to achieve efficient water level reduction in a desired range with good workability.

It is a figure which shows the example of application of the water pressure suppression method in 1st Embodiment. It is a figure which shows the example of application of the water pressure suppression method in 2nd Embodiment. It is a figure which shows the structural example 1 of a pressure reduction container. It is a figure which shows the structural example 2 of a pressure reduction container.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing an application example of the water pressure suppression method in the first embodiment. Here, in the situation where the ground portion 11 of the existing structure 10 is dismantled and only the underground portion 12 is reused, at least the bottom surface of the underground portion 12 is aquifer where groundwater 5 exists in the ground 2. The example which is located in the layer 1 and suppresses the water pressure will be described. Of course, the water pressure suppression method may be applied not only to the underground portion of the existing structure but also to the underground portion of the newly constructed structure.

  The underground portion 12 of the existing structure 10 is composed of a floor slab 13 and a side wall 14 that rises continuously from the side of the floor slab 13. In addition, on the ground 2 around the floor slab 13, the water stop / mountain wall 50 constructed to excavate the ground 2 and secure a dry construction area when the underground portion 12 is constructed is left.

  In the water pressure suppression method in the first embodiment, as shown in FIG. 1, a small diameter hole 110 is provided in the floor slab 13 in the inner region of the water stop / mountain wall 50, and a vacuum pump 120 connected to the hole 110. The groundwater 5 of the aquifer 1 is drained.

  The hole 110 is formed by coring the floor slab 13 so that the ground 2 directly below the floor slab 13 and the underground space 15 on the floor slab 13 are communicated with each other. Is airtightly fixed. If water pressure is applied to the side wall 14, the side wall 14 may be provided with a hole 110 and a valve mechanism 113 attached thereto.

  The valve mechanism 113 has a pipe 121 connected to a decompression vessel 122 installed in the underground space 15. The pipe 121 is a pipe in which the inner space 111 of the hole 110 communicates with the decompression vessel 122 through the inner space 114 of the valve mechanism 113. When the drainage operation from the hole 110 is not necessary, the valve of the valve mechanism 113 is closed, and the hole 110 and the pipe 121 are shut off in an airtight and watertight manner.

  The decompression container 122 connected to the pipe 121 is a sealed container having a certain strength, and a vacuum pump 120 is connected in addition to the pipe 121. The vacuum pump 120 is a device that applies a negative pressure to the hole 110 connected in a state where the valve mechanism 113 is open. Further, in the inner space 123 of the decompression container 122, a water storage container 124 for storing the groundwater 5 discharged through the hole 110 and the pipe 121 and a water for draining the groundwater 5 stored in the water storage container 124 to the ground surface 3 are stored. A pump 118 is also installed.

  The floor slab 13 having the above-described configuration and in contact with the bottom surface of the aquifer 1 is subjected to upward water pressure on the ground water 5. If the groundwater 5 naturally flows from the layer 1 and the valve mechanism 113 is opened, the groundwater 5 is self-injected into the underground space 15 (the water storage container 124) through the pipe 121. In this way, the amount of the groundwater 5 jetted from the hole 110 is in accordance with the difference between the atmospheric pressure in the underground space 15 and the water pressure acting directly below the floor slab 13. Therefore, the vacuum pump 120 connected to the hole 110 via the decompression container 122 and the valve mechanism 113 is operated, and the inner space 111 of the hole 110, the inner space 114 of the valve mechanism 113, the pipe 121, and further the inside of the decompression container 122. The air 123 is sucked and its negative pressure is increased. Then, the internal airs 111 and 114 and the internal air 123 of the decompression vessel 122, which have a corresponding negative pressure according to the suction of the vacuum pump 120, have a large pressure difference from the water pressure of the groundwater 5 in the ground 2, and accordingly. A wider range of groundwater 5 in the aquifer 1 is drawn into the inner space 123 of the decompression vessel 122 through the hole 110.

  As a result, in addition to the groundwater 5 self-injecting into the underground space 15 through the hole 110, the groundwater 5 sucked by the negative pressure acting on the hole 110 is also introduced into the underground space 15 (the inner space 123 of the decompression vessel 122). These groundwaters 5 are stored in the water storage container 124 together. This groundwater 5 is drained to the surface 3 by a submersible pump 118.

  Note that the vacuum pump 120 that applies a negative pressure to the inner space 111 of the hole 110 is disposed on the floor slab 13 as described above, and is located at a depth close to the groundwater level directly below the floor slab 13. Yes. Therefore, the negative pressure generated by the vacuum pump 120 sucks the inner space 111 and the like of the hole 110 without a large loss, and drains the groundwater 5 efficiently. Therefore, as in the well point method, the suction operation of the groundwater 5 directly under the floor slab 13 is performed after passing a long distance from the ground surface 3 and further over the water stop / mounting wall 50, so that the negative pressure is lost. There is no problem of efficient drainage and therefore no suppression of water pressure.

  Further, the output of the vacuum pump 120 is controlled in accordance with the magnitude or rate of change of various observation values such as stress generated in the floor slab 13 so that the water pressure applied to the floor slab 13 is reduced to an appropriate range assumed. It is preferable to drain the groundwater 5 while adjusting the magnitude of the negative pressure to be generated. Thereby, the water pressure concerning the underground part 12 of the existing structure 10 can be suppressed reliably and efficiently. In addition, since the vacuum pump 120 is controlled in this way and the water pressure can be suppressed with respect to the underground portion 12 of the target existing structure 10, an inappropriate groundwater level drop due to excessive drainage occurs in the surrounding environment. You can avoid doing that.

  Such an effect is achieved with a very simple and small-scale apparatus configuration including a combination of a small-diameter hole 110 provided in the floor slab 13 and the side wall 14 and a valve mechanism 113, a decompression vessel 122, a vacuum pump 120, a submersible pump 118, and the like. Therefore, good workability can be achieved even in the underground space 15 where the construction space tends to be limited.

  Further, the negative pressure generated by the vacuum pump 120 acts on the decompression vessel 122 having a larger volume than the small-diameter hole 110 and the valve mechanism 113, and the negative pressure applied to the hole 110 via the decompression vessel 122 is It is easier to be stable than when acting directly on the hole 110. Therefore, the amount of groundwater 5 pumped from the aquifer 1 through the self-injection well 130 and the hole 110 is also stabilized.

  Subsequently, a second embodiment in which a self-injection well 130 is further provided in the ground 2 below the hole 110 in the above-described water pressure suppression method will be described. FIG. 2 is a diagram illustrating an application example of the water pressure suppression method in the second embodiment. The self-injection well 130 in the second embodiment is a small-diameter well that is continuous with the lower opening of the hole 110 described in the first embodiment and reaches the aquifer 1 in the ground 2 from directly below the floor slab 13. Relief wells can be used. In this self-injection well 130, the ground 2 is drilled to the aquifer 1 to form a well hole 131, a well pipe 132 is inserted into the well hole 131, and then the outer periphery of the well pipe 132 and the wall surface of the well hole 131 are formed. It is constructed by stuffing with a filter material 133 such as sand gravel. A portion of the well pipe 132 corresponding to at least the depth of the aquifer 1 is a screen, and the groundwater 5 flowing from the aquifer 1 into the inner space 135 of the well pipe 132 through the filter material 133. Is filtered.

  In such a configuration, when a negative pressure is applied to the hole 110 by the vacuum pump 120 via the decompression vessel 122, the valve mechanism 113, and the like, this negative pressure is passed through the inner space 111 of the hole 110 and the well pipe 132 in the self-injection well 130 It acts on the inner space 135. The inner space 135 in which the negative pressure is applied has a large pressure difference from the water pressure of the groundwater 5 of the aquifer 1, and therefore the groundwater 5 of the aquifer 1 is drawn through the filter material 133 and the screen. . Since sufficient negative pressure is applied by the vacuum pump 120, the groundwater 5 in the well 135 inside the well 135 rises, and the water storage container in the underground space 15 through the hole 110 and the pipe 121 connected to the self-injection well 130 at the top. It is led to 124 and drained by the submersible pump 118. By forming and using the self-injection well 130 that can reach the aquifer 1 and collect the groundwater 5 directly under the hole 110, as a result, efficient drainage and water pressure suppression can be performed. .

  Next, a more specific method for applying a negative pressure to the hole 110 and the self-injection well 130 will be described with reference to FIG. FIG. 3 is a diagram illustrating a first structural example of the decompression vessel 122. Here, an example in which water pressure suppression is performed in a configuration in which the inner space 123 of the decompression vessel 122 described above is partitioned by a weir plate 126 is shown. In this example, the decompression vessel 122 has an inner space 123 divided into two by a dam plate 126. A pipe 121 of the valve mechanism 113 is connected to the section 127 (first section). A submersible pump 118 is installed in the section 128 (second section).

  When the vacuum pump 120 is operated, the inner space 123 of the decompression vessel 122 is depressurized, and negative pressure acts on the inner space 114 of the valve mechanism 113, the inner space 111 of the hole 110, and the self-injection well 130 via the pipe 121. . Then, similarly to the case of the first and second embodiments described above, the groundwater 5 is guided to the inner space 123 of the decompression vessel 122 through the pipe 121. The groundwater 5 that has entered the inner space 123 through the pipe 121 flows into the section 127 from the tip of the pipe 121. When the inflow of the groundwater 5 from the pipe 121 continues for a certain time, the section 127 is filled with the groundwater 5, and the groundwater 5 exceeding the capacity of the section 127 overflows the weir plate 126. The groundwater 5 that has overflowed the weir plate 126 flows into the section 128 and is drained to the ground surface 3 by the submersible pump 118.

  By configuring the inner space 123 of the decompression vessel 122 in such a configuration, in the section 127 to which the pipe 121 is connected, the ground water 5 is filled with water after a certain period of time, and as a result, the water level is kept constant. As a result, the volume of the inner air 123 of the decompression vessel 122 is also constant, and the negative pressure applied to the inner air 123 becomes stable. Therefore, the amount of groundwater 5 pumped from the aquifer 1 and drained is also stabilized.

  Although the example corresponding to the situation where the number of pipes 121 is one was shown in the above description, there may be a situation where groundwater 5 from a plurality of pipes 121 is processed. Therefore, a mode in which the inner space 123 of the decompression vessel 122 is appropriately partitioned by the weir plate 126 and the groundwater 5 from the plurality of pipes 121 can be treated will be described below. FIG. 4 is a view showing Structural Example 2 of the decompression container, and is an upper cross-sectional view of the inner space 123 of the decompression container 122.

  In this example, the inner space 123 of the decompression vessel 122 is divided into a plurality of barrier plates 126 to form a plurality of compartments 127 (first compartments). In the example shown in FIG. 4, the plurality of compartments 127 are arranged in a ring shape in the inner space 123 of the decompression vessel 122. One pipe 121 is connected to each section 127, and the groundwater 5 discharged from each pipe 121 flows into the corresponding section 127.

  On the other hand, the center of each compartment 127 grouped in a ring shape, that is, the center of the inner space 123 of the decompression vessel 122 is surrounded by the dam plate 126 of each compartment, and the compartment 129 (second compartment) common to each compartment 127 and Become. Therefore, the groundwater 5 in any section 127 that has overflowed the weir plate 126 in each section 127 filled with the groundwater 5 flows into the section 129. A submersible pump 118 is installed in the section 129, and the groundwater 5 that has flowed in is drained to the ground surface 3 by the submersible pump 118.

  According to this, the groundwater 5 collected from the plurality of holes 110 and the self-injection wells 130 is guided to each section 127 in the inner space 123 of the decompression vessel 122 and stored for each section. Only the groundwater 5 that has overflowed from the section 127 via the dam plate 126 is collected in the section 129 common to each section (one section shared by each pipe) and drained to the surface 3 by the submersible pump 118. Become. Therefore, in each section 127 to which the pipe 121 communicating with each hole 110 and the self-injection well 130 is led, even if there is a difference in the water collection speed for each hole 110 and the self-injection well 130, all of them become full over time. Thus, the water level is kept constant, and the volume of the inner air 123 of the decompression vessel 122 is also constant. Therefore, it becomes easy to stably apply a negative pressure to the inner space 123 of the decompression vessel 122, and the amount of groundwater 5 that collects water from the plurality of holes 110 and the self-injection well 130 and drains it to the ground surface 3 is also easily stabilized. .

  As mentioned above, according to this embodiment, it becomes possible to implement | achieve the efficient water level fall in a desired range with favorable workability.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 Aquifer 2 Ground 3 Ground surface 5 Groundwater 10 Existing structure 11 Above-ground part 12 Underground part 13 Floor slab 14 Side wall 15 Underground space 50 Water stop / mountain wall 110 Hole 111 Inside of hole 113 Valve mechanism 114 Inside of valve mechanism Empty 118 Submersible pump 120 Vacuum pump 121 Piping 122 Depressurized container 123 Inner space 124 of decompressed container Water storage container 126 Dam plate 127 Section (first section)
128 sections (the other section)
129 Other compartment 130 common to each compartment Self-injection well 131 Well hole 132 Well pipe 133 Filter material 135 Inner space of well pipe

Claims (5)

  A hole communicating with the inside and outside of the underground structure is formed in the part of the underground structure that contacts the groundwater, and a negative pressure is applied to the hole by a vacuum pump, so that the groundwater outside the underground structure flows into the underground structure. The water pressure suppression method characterized by the above-mentioned.   Drilling a well from the hole to the formation at a predetermined depth, applying a negative pressure to the hole with a vacuum pump, and flowing the groundwater outside the underground structure collected through the well into the air in the underground structure The water pressure suppression method according to claim 1, wherein:   The pipe connected to the hole is connected to the inner space of the predetermined container, and the inner space of the predetermined container is depressurized by a vacuum pump, so that the groundwater outside the underground structure collected through the hole is placed in the predetermined container. The water pressure suppression method according to claim 1 or 2, wherein the groundwater discharged and discharged into the predetermined container is drained by a submersible pump.   The inside of the predetermined container is partitioned by a dam plate, the pipe is connected to the first partition to discharge the groundwater, and the groundwater flowing from the first partition over the dam plate to the second partition is submerged in water. The method for suppressing water pressure according to claim 3, wherein the water is drained by a pump.   The first compartment in the predetermined container is divided into a plurality of sections, pipes are connected to the sections, and the groundwater flows from the respective pipes into the corresponding sections to which the pipes are connected. The water pressure suppression method according to claim 4, wherein the groundwater that has flowed over and flows into the second section common to the first section is drained by a submersible pump.