JP2006057275A - Water stop material of underground structure and cut-off method making use of the water stop material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water stop material capable of maintaining a cut-off function excellent over a long period of time at a low cost. <P>SOLUTION: The water stop material for stopping water by providing it in a void in an underground structure is formed by compounding bentonite, a thermoplastic resin, a plasticizer and a water absorptive resin as main ingredients. The bentonite of 30 to 40 wt.%, the thermoplastic resin of 30 to 35 wt.%, the water absorptive resin of 5 to 15 wt.% and the plasticizer of 15 to 20 wt.% are respectively compounded to mold the water stop material. It is heated at a high temperature after the mixture of the thermoplastic resin and the plasticizer, and the thermoplastic resin heated at the high temperature is compounded with other main ingredients to mold the water stop material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a structure constructed by combining tunnel segment members such as electric power, telegraph cable pipes or sewer pipes, and is attached to the gaps of other underground structures, or is interposed by compression or the like. The present invention relates to a water-stopping material that stops water leakage by closing water leaks such as gaps in underground structures and a water-stop method using the water-stopping material.

When constructing an underground structure, especially a tunnel segment (hereinafter simply referred to as a “segment”), the backfilling of the injected material is performed between the ground and this segment, until the injected material solidifies. Primary water stop and then secondary water stop to prevent long-term groundwater leakage into the tunnel. For this reason, when connecting the joints of the joint surfaces 22 on the two adjacent sides of a segment which is a curved plate body as shown in FIG. Water stop material is used, and water does not enter the inside of the segment due to the action of both of them.
As such a water-stopping material, the water-stopping material B made of water-expanded rubber is excellent in terms of workability and water-stopping performance, and is often used (it seems to be about 90% of the market). The water-stopping material B made of water-swelling rubber is a fixed-form material obtained by vulcanization molding of water-swelling resin such as a highly water-absorbing polymer and synthetic rubber, and is attached to the joint surface 22 of the segment 21 using an adhesive during construction. It will be installed.

  The water-stopping material made of water-expanded rubber affixed to the joint surface is compressed by the tightening force of the bolts and nuts when assembling the segments during construction, and the water-stopping material is stopped by the elastic repulsive force of the water-stopping material. Do. Even if the seam opens at the seam at a later date and the elastic repulsive force is reduced, as shown in FIG. 14, when water is absorbed, it self-expands and a force that expands in the direction of the arrow acts. If the surface stress σ due to this elastic repulsion force or self-expansion is greater than the water pressure P applied from the outside of the segment, the water stop function is maintained. That is, the basic condition of water stoppage due to the packing effect is that the contact stress σ> water pressure P.

In addition, there is a bentonite type as a water stop material. This is a plastic water-stopping material formed by kneading asphalt, petroleum-based wax or the like and bentonite, which is a water-swellable clay, and molding them. This water-stopping material performs water-stopping by the expansion of bentonite when it absorbs water, such as asphalt and petroleum wax, water tightness, flexibility, and adhesiveness. The bentonite used here is naturally produced, has been used for a long time as a civil engineering building material, and is inexpensive as a water-stopping material.
JP2000-110696 JP 2001-20692 A

  However, the underground water pressure where underground structures using such water-stopping materials are constructed increases the underground water pressure as the depth increases, and this water-stopping material is used as a gap between underground structures for a long period of time. There was a problem in maintaining the water function. That is, in the case of the water-stopping material made of the above-mentioned water-swelling rubber, the water-stopping material is stopped from a drop in elastic resilience accompanying long-term stress relaxation or a drop in water-swelling property due to outflow of superabsorbent polymer due to repeated water-absorbing drying. There was a risk that the water function would deteriorate. Moreover, in the case of the water-stopping material made of this water-expanded rubber, the construction cost was increased due to the high price.

  In addition, the latter bentonite water-stopping material is inexpensive, but the bentonite, which is a water-swellable substance, is inorganic, so it has reliability such as durability, but its swelling performance is low, so it absorbs moisture and after expansion It was inferior to the following ability. That is, it is not performed to such an extent that swelling is expected. As a result, it was inferior in reliability by long-term use. Furthermore, since this water-stopping material has plasticity, it does not have sufficient restoring force and elastic repulsive force. When it receives a compressive force such as pressure (thrust) of a jack for tunneling, it will cause plastic deformation and maintain the water-stop function. It had the problem of becoming difficult.

  Therefore, the present invention solves the above-mentioned problems by providing an inexpensive water-stopping material that maintains an excellent water-stop function over a long period of time and a water-stop method using the water-stopping material.

  The invention of claim 1 is a water-stopping material that is provided in a gap in an underground structure to stop water, and is an underground structure formed by blending bentonite, a thermoplastic resin, a plasticizer, and a water-absorbing resin as main raw materials. A waterstop material was used. Further, the invention of claim 2 contains 30-40% by weight of the bentonite, 30-35% by weight of the thermoplastic resin, 5-15% by weight of the water-absorbing resin, and 15-20% by weight of the plasticizer. The water-stopping material for the underground structure according to claim 1 was molded. Further, the invention according to claim 3 is the method according to claim 1 or 2, wherein the thermoplastic resin is mixed with the plasticizer and heated at a high temperature, and the thermoplastic resin heated at the high temperature is blended with the other main raw material. A water-stopping material for the underground structure described in Crab.

  According to a fourth aspect of the present invention, there is provided the water stoppage material for the underground structure according to any one of the first to third aspects, interposed in a gap between the underground structures, and leaking water that permeates through the gaps in the underground structure. It was set as the water-stopping method of the underground structure which expands by the water-absorbing material bentonite and the water-absorbing resin absorbing water and closes the gap to stop the water. According to a fifth aspect of the present invention, the water-stopping material for the underground structure according to any one of the first to third aspects is compressed and interposed in the gap between the underground structures to close the gap and stop the water. If there is further gap in the location and there is water leakage, water will be stopped by the restoring force and elastic repulsion of the water stop material in the short term, and the bentonite and water absorbent resin will absorb water in the long term. The water-stopping method of the underground structure that swells and closes the gap to stop the water.

  According to each of the first to fifth aspects of the present invention, the rubber has an appropriate rubber elasticity, has excellent followability at the time of construction, and the gap due to the openings of the joints of the underground structure due to the fluctuation of the underground structure after the construction. Even if it occurs, the gap is closed due to the followability by the expansion of the water stop material. Furthermore, even if a crack or the like occurs in the water-stopping material, the water-stopping function can be maintained by self-sealing. While exhibiting such an excellent water-stopping effect, it is inexpensive because it uses bentonite and can be widely used for water-stopping in underground structures, greatly contributing to a reduction in construction costs. In addition, bentonite used in this water-stopping material is stable for a long time because it does not deteriorate or rot, and has excellent performance such as excellent durability because it does not decrease expandability due to repeated water absorption and drying. .

  According to invention of Claim 2, since the structure of each compounding material was limited, the water stop effect can be exhibited more reliably. According to the invention of claim 3, since the thermoplastic resin heated at a high temperature after being mixed with the plasticizer is blended with the other main raw material and molded, the elastic force of the waterstop material can be surely exhibited. . Furthermore, according to each of the inventions of claims 4 and 5, when a water-stopping material is provided in the gap of the underground structure and the gap is closed to stop the water, and when there is a gap in this portion and water leakage occurs, The water-stopping material is stopped by the restoring force and elastic repulsion, and in the long term, the bentonite and the water-absorbing resin of the water-stopping material swell and absorb the water to close the gap. The water stop effect can be demonstrated.

  30 to 40% by weight of bentonite, 30 to 35% by weight of thermoplastic resin, 5 to 15% by weight of water-absorbing resin, and 15 to 20% by weight of plasticizer were blended as main raw materials, respectively. Further, after mixing with the plasticizer, the thermoplastic resin heated at high temperature was blended with the other main raw material to form a water-stopping material.

  Furthermore, when the water-stopping material of these underground structures is compressed and interposed in the gaps of the underground structures to close the gaps and stop the water, and when there are further gaps in the areas and there is water leakage, The water is stopped by the restoring force and elastic repulsion of the water-stopping material, and in the long term, the bentonite and the water-absorbing resin of the water-stopping material swell to absorb water and close the gap to stop the water.

Embodiments of the present invention will be described below with reference to the drawings.
The waterstop material of the present invention is mainly molded from bentonite, a thermoplastic resin, a plasticizer, and a water-absorbing resin, and these are blended and molded. Bentonite is mainly composed of montmorillonite and is formulated for the purpose of exhibiting properties such as swelling, water-stopping properties, and adhesiveness. However, if the amount of bentonite is too large, the elastic performance of the water-stopping material as a whole will increase. descend. The molded water-stopping material has bentonite particles uniformly dispersed in the thermoplastic resin particles and the like.

  The thermoplastic resin (TPR) has rubber elasticity at normal temperature but plasticizes at high temperature. Therefore, this water-stopping material is used by mixing with other materials after high-temperature overheating for the purpose of exerting elastic force. . Depending on the main component of this thermoplastic resin, olefin (TPO), styrene (TPS), diene, ester (TPEE), urethane (TPU), amide (TPEA), vinyl chloride (TPVC), etc. There are many types available. Examples of the styrene resin include SEEP type, and examples of the diene resin include 1,3-pentadiene.

  The plasticizer is generally called process oil and is a kind of oil obtained by refining petroleum, and by blending it with the thermoplastic resin, the processability is facilitated, or Although it mix | blends in order to provide a softness | flexibility, the kind of plasticizer is limited for every kind of synthetic resin.

  The water-absorbent resin is basically the same as that used for a general water-swelling water-stopping material, and is blended with the expectation of swelling performance. In view of swelling speed and hardness after swelling, polyethylene oxide (PEO) is used here.

  Although a water-stopping material can be obtained by mixing these blends, it is desirable to mix them sufficiently so that the particles of each blend are uniform. Moreover, in order to improve the properties of this water-stopping material, various additives that have been used in conventional water-stopping materials can be blended as necessary. Examples of the additive include softeners (mineral oil, synthetic oil, fatty oil, etc.), stabilizers (surfactants, amines, phenols, etc.), antioxidants, colorants, fillers and the like.

  The method of forming this water-stopping material is the same as that of a conventional water-stopping material, and an extrusion molding method, a press molding method, or the like can be used. Although the shape of the water-stopping material formed here is various, it is desirable to select a shape that can provide a sufficient water-stopping function and an optimal shape that does not hinder the construction.

Next, the compounding example of these main raw materials is shown.

  As described above, four examples of Bt-1, Bt-2, Bt-3, and Bt-4 were molded as blending examples of the water-stopping material of this example. Further, as comparative examples, Rb-1 and Rb-2, which are water-stopping materials made of conventional water-expanded rubber, were molded. These Rb-1 and Rb-2 are based on vulcanized rubber (chloroprene, butyl, nitrile, etc.) and a water-absorbing resin (SAP: sodium polyacrylate, hereinafter the same). The difference between Rb-1 and Rb-2 is that the blending amount of the water-absorbing resin in Rb-1 is blended more than the blending amount of the water-absorbing resin in Rb-2.

These six water-stopping materials were subjected to a water pressure resistance test and compared. The water pressure resistance test here was performed by using the joint at the time of connecting the segments. However, the water pressure test was performed on the assumption that the segments were flat without grooves. The maximum working water pressure used here was 1.0 Mpa≈10 kgf / cm ² corresponding to 100 m underground. The basic condition of the water stop was working water pressure <surface stress, and working water pressure was groundwater pressure. Further, it was considered that the contact stress is generated by the restoring force and elastic repulsion force of the water-stopping material in the short term, and is generated by the expansion of the water-stopping material in the long term. The results are shown in FIGS.

  First, the test results of Rb-1 and Rb-2, which are conventional water-stopping materials, are shown in FIG. In FIG. 2, the vertical stress is the contact stress (Mpa), and the horizontal axis is the working hydraulic pressure (Mpa). In addition, in order to see the movement of the contact stress with respect to the small movement of the working water pressure (groundwater pressure), the scale is taken at intervals of a value smaller than that of the vertical axis. Therefore, the line of working hydraulic pressure = contact stress extends to the right from a position of 0 at a small angle. On the other hand, the line 5 of Rb-1 is a large value exceeding this line 5, and when the working water pressure is 0 (Mpa), the contact stress is about 6.2 (Mpa). It is a line that gently falls from the position to a position where the working hydraulic pressure is 1.0 (Mpa) and the contact stress is about 5.0 (Mpa). Further, the line 6 of Rb-2 is a line 6 having a value exceeding the working hydraulic pressure line as in Rb-1, and when the working hydraulic pressure is 0 (Mpa), the contact stress is about 4.0 (Mpa). There is a line that gradually falls from this position to a position where the working water pressure is 1.0 (Mpa) and the contact stress is about 3.4 (Mpa). These facts indicate that both Rb-1 and Rb-2 were able to withstand the working water pressure in this test and were good in the water pressure resistance test (not long-term).

  FIG. 1 also shows the test results of Bt-1, Bt-2, Bt-3, and Bt-4. In FIG. 1, the tangential stress (Mpa) is taken on the vertical axis and the working hydraulic pressure (Mpa) is taken on the horizontal axis, as in FIG. 2, but the vertical axis has a smaller value than FIG. I took it at intervals. This is because the test results of Bt-1, Bt-2, Bt-3, and Bt-4 are concentrated between the contact stresses of 1.0 to 2.0 (Mpa). Again, the line with working hydraulic pressure = contact stress extends to the right from a position of 0 at a small angle, and each of Bt-1, Bt-2, Bt-3 and Bt-4 lines is this line. Exceeds value.

Here, the line 1 of Bt-1 has a contact stress of about 1.9 (Mpa) when the working water pressure is 0 (Mpa). From this position, the working water pressure is 1.0 (Mpa) and the contact stress is about 1 The line is almost unchanged up to a position of .9 (Mpa). The line 2 of Bt-2 has a contact stress of about 1.5 (Mpa) when the working water pressure is 0 (Mpa). From this position, the working water pressure is 1.0 (Mpa) and the contact stress is about 1.7 (Mpa). The line does not change much up to the position of Mpa). The line 3 of Bt-3 has a contact stress of about 0.9 (Mpa) when the working water pressure is 0 (Mpa). From this position, the working water pressure is 1.0 (Mpa) and the contact surface stress is about 1.2. The line is not much changed up to the position of (Mpa). Further, the line 4 of Bt-4 has a contact stress of about 1.25 (Mpa) when the working water pressure is 0 (Mpa). From this position, the working water pressure is 1.0 (Mpa) and the contact surface stress is about 1.5. The line is not much changed up to the position of (Mpa).
These indicate that all of Bt-1, Bt-2, Bt-3 and Bt-4 were able to withstand the working water pressure and were good in the water pressure resistance test (not long-term). ing.

  In these water pressure resistance tests, Bt-1, Bt-2, Bt-3 and Bt-4 in this example are not as high in contact stress as conventional Rb-1, Rb-2, but Rb-1, It became clear that it could withstand water pressure equivalent to 100m underground with Rb-2. Furthermore, each line of Rb-1 and Rb-2 in FIG. 1 is lowered to the right, and the values when the working hydraulic pressure is increased are both decreasing, indicating that the contact stress at these points was weak. However, the Bt-1, Bt-2, Bt-3, and Bt-4 lines are almost unchanged or tend to increase, and even if the working hydraulic pressure increases, it is stable if it is within the allowable range. I found out

  Next, Bt-1, Bt-2, Bt-3, and Bt-4 of the waterstop material of this example, and the number of days of immersion when tap water was infiltrated into each waterstop material of Rb-1 and Rb-2 The volume expansion ratio was tested and compared. The result is shown in FIG. As shown in FIG. 3, the Rb-1 line 11 shows a very high value compared to other water-stopping materials, and has a volume expansion ratio of about 6.5 times since about 12 and 3 days after immersion. Until about 57th and 8th days, the volume expansion ratio remained stable. The line 12 of Rb-2 is a moderately upward line compared to Rb-1, and was the lowest volume expansion ratio among the water-stopping materials tested this time. Around 57 and 8 days after the start of this test, the volume expansion ratio is about twice. Also, the Bt-1 line 7 and the Bt-2 line 8 show volume expansion ratios higher than Rb-2 and are similar to each other. About 3.1 times, Bt-2 line 8 shows a relatively large value of 3.7 times, and then shows a downward trend. Around 57 and 8 days, the volume expansion ratio is about 2.6 times, respectively. It is about. Further, the Bt-3 line 9 and the Bt-4 line 10 also show higher volume expansion ratios than the Rb-2 line 12, and are similar to each other, showing a moderate upward trend from the start of the test, 57 The volume expansion ratio is about 2.2 times around the 8th.

In these volume expansion ratio tests, the values of Bt-1, Bt-2, Bt-3, and Bt-4 are all between the values of Rb-1 and Rb-2. The volume expansion ratios of -1, Bt-2, Bt-3, and Bt-4 did not reach the volume expansion ratio of Rb-1, but were found to be higher than the volume expansion ratio of Rb-2.
From the results of these water pressure resistance tests and volume expansion ratio tests, the water-stopping materials of Bt-1, Bt-2, Bt-3 and Bt-4 of this example are compared with conventional water-stopping materials of Rb, It was found that there was no inferiority in terms of water pressure resistance and volume expansion ratio.

  Such a water stop material is used in the connection between the segments 21 and 21. As shown in FIG. 4, the water-stopping material A is attached to the joint surface 22 of one segment 21 using its own adhesiveness or a separate adhesive, and the portion and the joint surface 22 of the other segment 21 are attached. The joint surfaces 22, 22 of the two segments 21, 21 are fastened by bolts 23 and nuts 24. The joint surface may be tightened using a spring steel clip or the like. Further, when the water-stopping material A has a protective film or the like that protects its own adhesiveness, the protective film or the like is removed before the segment 21 is joined.

  In the water-stopping structure of the segment 21 provided with the water-stopping material A, the moisture that has entered the seam of the segment 21 has an appropriate rubber elasticity that the water-stopping material A attached to the joint surface 22 of the segment 21 has. Due to the followability and adhesiveness, the ingress of moisture from the relevant part to the inside is blocked, and the water is stopped. Moreover, even if the elastic force is strengthened by adding the thermoplastic resin and the compressive force or the water pressure is repeatedly applied, there is no possibility that the water stop function is deteriorated due to excessive plastic deformation. Further, even if a gap due to the opening is generated secondarily due to fluctuations in the segment 21, the bentonite or the water-absorbent resin in the water-stopping material absorbs water and swells, and the gap due to the opening is blocked to stop the water. Is done.

  Also shown in FIG. 5 is the connection of other types of segments 25. The difference from the segment 21 is that a concave portion 27 is provided on the joint surface 26 of the segment 25, and the water stop material A is attached to the concave portion 27 and the segments 25, 25 are fixed to each other with the bolt 23 and the nut 24. By sticking the water stop material A to the recess 27, the space expands in the space formed by the recesses 27, 27 of the two connected segments 25, 25, so that the water can be reliably stopped in this space. Further, in the case of the segment 25 in FIG. 5, the directionality of expansion is restricted, so that the water-stopping material of Bt-1 or Bt-2 having a high volume expansion ratio is suitable. In the case of the segment 21 in FIG. Therefore, the Bt-3 and Bt-4 water-stopping materials having a low volume expansion ratio are suitable.

  Further, FIG. 6 to FIG. 11 show the cross-sectional shape of the water-stopping material A, and any shape other than the rectangular shape may be used. Good. In FIG. 6, a protective film 28 is coated on one surface with a water-stopping material A1 formed so that its cross section is rectangular. This protective film 28 is effective for preventing the adhesiveness of the water-stopping material from deteriorating workability when the segment is packed and transported, etc., and during construction, and to prevent the water-stopping performance from being deteriorated. , Removed before the segments are connected. Moreover, what is shown in FIG. 7 is the water stop material A2 which provided two strips of semicircular ridges 29 on one surface of the water stop material formed so that the cross section is rectangular. FIG. 9 shows a water-stopping material A4 formed so that the cross section becomes a semicircular shape.

  FIG. 10 shows a water-stopping material A5 provided with a rubber elastic material layer 30 at the center of a material formed so as to have a rectangular cross section. FIG. 11 shows a plate-like rubber elastic material layer 31. This is a water-stopping material A6 in which concave portions 32 are provided on the respective front and back surfaces, and the water-stopping material is provided in these concave portions 32 and integrated.

  Such a water-stopping material A is fixed to the joint surface of the segment with an adhesive or an adhesive, and then the joint surface of the segment is tightened by a bolt 23 and a nut 24 to stop water with an appropriate rubber elastic followability. In the case where an opening or the like is generated at the joint between the joint plates, the bentonite or the water-absorbing resin in the water-stopping material absorbs water and expands and closes the gap, so that excessive plasticity can be obtained even if it is repeatedly subjected to water pressure and compressive force. There is no shape deformation and the water stop function does not deteriorate. Furthermore, bentonite in the water-stopping material is an inorganic mineral and has excellent durability, so that a highly reliable water-stopping effect can be obtained over a long period of time, and since it is inexpensive, it is economically excellent.

  In addition, in the said Example, although the specific compounding example of a water stop material is described as Bt-1, Bt-2, Bt-3, and Bt-4, the compounding example of the water stop material A is these. It is not limited to things. Moreover, although this water-stopping material A is affixed to the joint of the joint surfaces 22 and 26 of the segments 21 and 25, and it demonstrates in connection of the segments 21 and 25, the use of this water-stopping material A is the segments 21 and 25 Not only the connection between them, but also the waterproofing material A of 40-concrete joints in the open-cut method as shown in FIG. 12, the waterproofing material of concrete-seamed joints such as secondary lining, and repair of leaked points in existing structures It can be used as a water-stopping material for various purposes, such as a water-stopping material for underground use, a water-stopping material for cracks in underground structures, and other water-stopping materials for existing or newly installed underground structures. Furthermore, although polyethylene oxide (PEO) is used as the water absorbent resin, the water absorbent resin is not limited to polyethylene oxide (PEO). Although the shape of the water blocking material A is specifically described, these are not essential requirements of the present invention.

It is a graph which shows the result of the water-proof pressure test of the water stop material of the Example of this invention. It is a graph which shows the result of the water-proof pressure test of the conventional water stop material. It is a graph which shows the result of the test of the volume expansion ratio of the water stop material of the Example of this invention, and the conventional water stop material. It is sectional drawing which shows the state which is using the water stop material of the Example of this invention at the time of the connection of segments. It is sectional drawing which shows the state which uses the water stop material of the Example of this invention at the time of the connection of other segments. It is a perspective view of the state which shape | molded the water stop material of the Example of this invention so that a cross section might become a rectangle. It is a perspective view of the state where the water stop material of the example of this invention was formed so that a section might become a rectangle, and two semicircular ridges were provided on one side. It is a perspective view of the state which shape | molded the water stop material of the Example of this invention so that a cross section might become trapezoid. It is a perspective view of the state which shape | molded the water stop material of the Example of this invention so that a cross section might become a semicircle. It is a perspective view of the state which formed the water stop material of the example of this invention so that a section might become a rectangle, and provided the rubber elastic substance layer in the center. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a water-stopping material according to an embodiment of the present invention, in which a recessed water-stopping material provided on each of the front and back surfaces of a plate-like rubber elastic material layer is provided and integrated. It is explanatory drawing of the state which used the water stop material of the Example of this invention for the joint seam of the concrete casting in an open-cut method. It is explanatory drawing which shows the state which affixed the water stop material on the segment. It is explanatory drawing which shows the surface pressure (sigma)> water pressure P by the restoring force of a water stop material, an elastic repulsive force, and expansion which are the basic conditions of water stop.

Explanation of symbols

A Water-stopping material 21 Segment 22 Segment joint surface 23 Bolt 24 Nut 25 Segment 26 Segment joint surface 27 Recess 28 Segment protective film 29 Segment flange 30 Rubber elastic material layer 31 Rubber elastic material layer 32 Recess

Claims (5)

A water-stopping material that is provided in a gap in an underground structure and stops water,
A water-stopping material for underground structures, which is formed by blending bentonite, thermoplastic resin, plasticizer, and water-absorbing resin as main raw materials. 30 to 40% by weight of the bentonite, 30 to 35% by weight of the thermoplastic resin, 5 to 15% by weight of the water absorbent resin, and 15 to 20% by weight of the plasticizer, respectively. The waterstop material for an underground structure according to claim 1. The thermoplastic resin is mixed with the plasticizer and heated at a high temperature, and the thermoplastic resin heated at a high temperature is blended with the other main raw material and molded. The waterproof material for the underground structure described. The water stoppage material for an underground structure according to any one of claims 1 to 3 is interposed in a gap between the underground structures, and water leaking from the gaps in the underground structure is caused by bentonite and water absorption of the waterstop material. A water-stopping method for an underground structure, wherein the water-soluble resin expands by absorbing water and closes the gap to stop the water. The water-stopping material for an underground structure according to any one of claims 1 to 3 is compressed and interposed in a gap in the underground structure to block the gap and stop the water. In such a case, the water stoppage is stopped by the restoring force and rebound resilience of the waterstop material in the short term, and the bentonite and water absorbent resin of the waterstop material swell and absorb the water in the long term. A method for water-stopping an underground structure, characterized in that the water is closed and water-stopped.