JP2005113464A - Design method of joint part of steel sheet pile for impervious wall and joint part structure of steel sheet pile for impervious wall using this design method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a design method of a joint part of a steel sheet pile for an impervious wall, capable of surely securing water cut-off performance of the joint part, regardless of a fitting state of the steel sheet pile for the impervious wall. <P>SOLUTION: This design method of the joint part of the steel sheet pile for the impervious wall, cuts off water by restricting a water-swelling water cut-off material between the mutually opposed joint parts of the steel sheet pile. Maximum clearance between the joint parts, the thickness and a construction material of the water-swelling water cut-off material, are designed so that contact stress of the joint parts and the water-swelling water cut-off material after water-swelling, exceeds a water pressure difference on both sides of the steel sheet pile, even when the maximum clearance is generated between the joint parts by the fitting state of the steel sheet pile. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a joint portion of a steel sheet pile for a water shielding wall, and particularly relates to a joint structure of a water shield steel sheet pile for the purpose of preventing diffusion of contaminated water flowing out from a waste final disposal site or contaminated soil.

  A steel sheet pile may be used as a water-impervious wall at the final disposal site. In this case, the steel sheet pile is placed in the ground after applying a water-swellable water stop material in advance to the joint portion of the steel sheet pile. The water-swellable water-stopping material that expands by reacting with water in water or soil fills the gaps between the joints facing each other, thereby preventing water leakage from the joints (see Patent Documents 1 to 3).

  Various materials have been proposed as water-swellable water-stopping materials, but the use of a moisture-curing special polyurethane resin that swells about 5 to 10 times as shown in Patent Document 4 has been put into practical use and widely spread. doing.

  However, at the time of placing the steel sheet pile, a part of the water-swellable water-stopping material may be peeled off due to friction with the surrounding ground and the fitting to be fitted, which may adversely affect the water shielding performance. As a means for preventing the separation of the water-swelling waterproofing material due to contact between the joints, a groove groove is drilled in the axial direction of the fitting part of the joint, and a water-swellable water-stopping material is provided in the groove groove. A method of filling (refer to Patent Document 5), a method of providing a spacing holding projection (refer to Patent Document 6), a method of ensuring a gap for mounting a water-stopping material in a male and female non-identical cross-sectional shape (refer to Patent Document 7) ) Has been devised.

Japanese Utility Model Publication No. 46-33977 Japanese Patent Publication No. 47-43612 Japanese Patent Publication No. 6-96688 Japanese Patent No. 1737445 Utility Model Registration No. 2093395 JP 2000-192451 A Japanese Unexamined Patent Publication No. 2000-192452

  In general, the joint portion of the steel sheet pile is made so that a gap is generated when it is fitted in consideration of workability at the time of placing on the ground. In the water leakage prevention method for the joint portion using the water-swellable water-stopping material, the gap is filled by the volume expansion of the water-stopping material to prevent the formation of a water channel. The conventional design method is based on the idea that a water-swellable water-proof material that does not allow water to pass through should be filled in the gap, that is, the ratio between the volume of the applied water-swellable water-proof material and the volume of the gap. The coating amount was determined according to the idea that the gap was closed if the volume expansion coefficient of the water-swellable water-stopping material was smaller.

  However, the amount of gap between the steel sheet pile joints is not constant. In the case of a U-shaped steel sheet pile, a gap of about 2 to 5 mm is generated in the neutral state. On the other hand, when the adjacent steel sheet pile is in the most compression side, a gap of about 10 mm is generated in the joint portion. When it comes to the side, the bottom part of the joint part to which the water blocking material is applied comes into contact with the opposing joint part. If a gap of about 10 mm is generated between the joints, the water-swellable water-stopping material may not be able to completely fill the gaps in the joint, and the expansion pressure of the water-swellable water-stopping material may be due to the water pressure difference between both surfaces of the impermeable walls. Therefore, the water channel was deformed to form a water channel, which could cause water leakage from the joint.

  Therefore, the present invention provides a design method for a joint portion of a steel sheet pile for a water shielding wall and a structure of the joint portion that can reliably ensure the water stop performance of the joint portion regardless of the fitting state of the steel sheet pile for a water shielding wall. For the purpose.

  In order to solve the above problem, the present inventor applied the principle that the contact stress at the contact surface between the swollen water-swelling water-stopping material and the joint portion does not leak if the contact stress is greater than the working water pressure. The maximum gap between joints, the thickness and material of the water-swellable water stop material so that the contact stress of the water-swellable water stop material exceeds the water pressure difference on both sides of the steel sheet pile even if there is a maximum gap between them Designed.

  That is, the invention according to claim 1 is a method for designing a joint portion of a steel sheet pile for a water shielding wall in which a water-swellable water-stopping material is constrained between joint portions of steel sheet piles facing each other. The maximum gap between the joints and the water swelling so that the contact stress between the joint and the water-swellable water-stopping material after water swelling exceeds the water pressure difference on both sides of the steel sheet pile even when there is a maximum gap between them. It is characterized by designing the thickness and material of the water-resistant waterproof material.

  The invention of claim 2 is a method for designing a joint portion of a steel sheet pile for a water-impervious wall according to claim 1, wherein a water-swellable water-stopping material having a predetermined thickness and material is used. The relationship between the joint portion and the contact stress between the water-swellable water-stopping material after water swelling is obtained in advance, and the maximum gap between joints, the thickness of the water-stopping material, and the material should be designed based on this relationship. Features.

  The invention of claim 3 is the design method of the joint portion of the steel sheet pile for a water shielding wall according to claim 1 or 2, by providing a recess in which one of the joint portions accommodates a water-swellable water stop material, The gap between the other joint portion and the water swellability before water swelling is increased, and the thickness of the water-swellable water-stopping material is increased.

  Invention of Claim 4 is a design method of the joint part of the steel sheet pile for water-impervious walls of Claim 3, The cross-sectional shape of the water-swellable waterproofing material before water swelling is substantially 8-18 mm in diameter. The protrusion amount from one side of the joint part of the water-swellable water-stopping material before water swelling is set to 1 to 2 mm.

  The invention according to claim 5 is a joint structure of a steel sheet pile for a water shielding wall that restrains a water-swellable waterproofing material between joint sections facing each other in steel sheet piles. Even when a gap occurs, the contact stress between the joint portion and the water-swellable water-stopping material after water swelling exceeds the water pressure difference on both sides of the steel sheet pile.

  The invention according to claim 6 is that in the joint structure of the steel sheet pile for a water shielding wall according to claim 5, a recess in which the water-swellable water-stopping material is accommodated is formed in one of the joint portions facing each other. Features.

  The invention according to claim 7 is the joint structure of the steel sheet pile for a water shielding wall according to claim 6, wherein the cross-sectional shape of the water-swellable water-stopping material before water swelling is a substantial circle having a diameter of 8 to 18 mm. It is set to a shape, and the amount of protrusion of the water-swellable water-proof material before water swelling from one of the joint parts is set to 1 to 2 mm.

  According to the first aspect of the present invention, the water stoppage of the joint portion can be reliably ensured regardless of the fitting state of the steel sheet pile for the water shielding wall.

  According to the invention of claim 2, the relationship between the gap between the joint portions and the contact stress is obtained in advance, so that the maximum gap between the joint portions and the water-swellable water stop material can be easily designed.

  In general, increasing the thickness of the water-swellable water-stopping material increases the allowable clearance of the joint (details will be described later), which is advantageous in terms of workability when manufacturing steel sheet piles and placing on the ground. . However, if the thickness of the water-stopping material before swelling is large, the fitting resistance of the joint part increases when it is placed on the ground, or the water-swellable water-stopping material is caused by friction with the opposing joint part or the ground. Peel off. For this reason, in invention of Claim 3, by providing the hollow in which a water-swellable water-stopping material is accommodated in a joint part, and accommodating most parts of a water-swellable water-stopping material, thickness is protected, protecting a water-stopping material. Secured.

  According to invention of Claim 4, since the protrusion amount of a water swellable water stop material is set to 1-2 mm, the fitting resistance of a joint part increases at the time of driving to the ground, There is no possibility that the water-swellable water-stopping material will peel off due to friction with the ground. Moreover, when the diameter of the water-swellable water-stopping material is 8 mm or less, water-stopping becomes difficult, and when it is 18 mm or more, it is difficult to manufacture a steel sheet pile.

  Moreover, this invention may be comprised as invention of the joint part structure of the steel sheet pile for water-impervious walls as described in Claims 5-7.

  Hereinafter, an embodiment of a method for designing a joint portion of a steel sheet pile for a water shielding wall according to the present invention will be described with reference to the accompanying drawings.

  First, an example of designing a U-shaped steel sheet pile in which a recess filled with a water-swellable water-stopping material (hereinafter referred to as a water-stopping material) is formed on the inner surface side of the joint portion in a cross-sectional view will be described. FIG. 1 shows a steel sheet pile in which such a depression is formed. This steel sheet pile includes a horizontal web 1 in a cross-sectional view, a flange portion 2 whose both ends in the width direction are inclined in the same direction, and a claw-shaped joint portion 3 (so-called Ralzen) provided at the tip of the flange portion 2. A joint). On the inner surface side of the nail bottom portion of the joint portion 3, a recess 4 for accommodating a water stop material is formed by hot rolling.

  FIG. 2 shows a cross-sectional view of the pair of joint portions fitted. The recess 4 of the joint portion 3 accommodates most of the water blocking material 6 (water-expandable elastic rubber seal material) having a circular cross section. When the joint portions 3 and 3 of the steel sheet piles facing each other are fitted in consideration of workability at the time of placing on the ground, the inner surface of the claw bottom portion of one joint portion 3 and the other joint portion 3 A gap is formed between the nail tip 5 and the outer surface. In the case of a U-shaped steel sheet pile, a gap amount gn of about 2 to 5 mm is generated in the neutral state shown in FIG. On the other hand, as shown in FIG. 2B, when the fitting state of the adjacent steel sheet piles is the most compressed side, a gap of about 10 mm is generated in the joint portions 3 and 3. A gap generated between the joint portions 3 and 3 when the fitting state is the most compressed side is defined as a maximum gap amount gmax.

  As shown in FIG. 3, in order for water leakage not to occur when the gap between the joints becomes maximum after the waterstop 6 swells, the contact stress between the waterstop 6 and the joint is steel. It is necessary to exceed the water pressure difference between both sides of the sheet pile (the working water pressure Pw acting on the water stop material). In other words, if the water pressure difference exceeds the contact stress σ, the water blocking material 6 is deformed and water leaks. This principle of water stoppage is applied to the design method of the present invention.

  A specific design method will be described below. First, the relationship between the gap between the joints and the contact stress between the joint and the water-swellable water-swelled material after water swelling when a water-swellable water-proof material of a predetermined thickness and material is used is obtained. . In this embodiment, in order to evaluate the contact stress of the water-stopping material, a test body simulating the depression of the joint is manufactured, and the water-stopping material made of a water-expandable elastic rubber seal material is immersed in water for 2 weeks to swell the water. In this state, the relationship between the gap amount and the reaction force was measured. The cross-section of the water blocking material is circular (in this case, the diameter of the circle corresponds to the thickness). Since the contact area changes according to the gap amount, the contact lengths at both ends of the water stop material are also measured at each load stage. FIG. 4 shows a schematic diagram of the test apparatus.

  FIG. 5 plots the relationship between the amount of clearance between joints and the contact stress of the water stop material when a water stop material having a circular cross section is accommodated in the recess of the joint portion. When the water-stopping material has a diameter of 8 mm or less, water-stopping becomes difficult. When the diameter of the water-stopping material is 18 mm or more, it is difficult to manufacture a steel sheet pile. For this reason, the diameter of a water stop material prepared three types, 8 mm, 12 mm, and 18 mm. The inner diameters of the corresponding recesses are 8 mm, 12 mm, and 17 mm, respectively. Moreover, the test body of each diameter was tested by the type which made the opening width of the hollow the same dimension as an internal diameter, and two types slightly narrower than the internal diameter. Although the depth of the dent is also considered as a parameter, the depth h of the water-stopping material is determined to be about 1 to 2 mm (see FIG. 2) within the range of the depth that can be manufactured. The amount of protrusion is determined so that the water stop material that is not water-expanded does not contact the opposing joint when the fitting state of the joint is neutral. FIG. 5 shows the relationship between the contact stress and the gap amount of the type in which the opening width of the depression is the same as the inner diameter. Although not shown in FIG. 5, the effect of the opening width was relatively small except when the gap amount was as small as 2 mm or less. According to FIG. 5, it can be seen that, generally, the contact stress generated in the waterstop material increases as the gap amount increases.

  Next, the maximum gap between the joints and the diameter of the water-swellable water-stopping material are determined so that the contact stress between the joint and the water-swellable water-stopping material after water swelling exceeds the water pressure difference on both sides of the steel sheet pile. . If the target water stop pressure is 0.2 MPa (corresponding to a water head difference of 20 m), for example, the maximum allowable gap amount required for the contact stress to exceed the water stop pressure is obtained. At this time, when the relationship between the rubber seal material diameter and the maximum allowable gap amount is plotted, the relationship as shown in FIG. 6 is obtained. From FIG. 6, the relationship between the maximum value of the gap amount that can be stopped when the water pressure difference between both sides of the steel sheet pile is 0.2 MPa and the diameter of the water stop material is obtained. By the above method, the relationship between the diameter of the water-stopping material that does not cause water leakage due to a predetermined water pressure difference and the maximum value of the gap amount of the joint is obtained regardless of the fitting state of the joint. In addition, it is only necessary to use a steel sheet pile having a maximum allowable gap amount or less, but when adjusting the maximum allowable gap amount of the steel sheet pile, the bending angle of the joint claw tip may be changed. However, the thickness of the joint portion may be increased.

  Also, as shown in FIG. 6, increasing the diameter of the water stop material increases the allowable clearance of the joint, which is advantageous in terms of workability when manufacturing steel sheet piles and placing on the ground. However, when the volume of the water-stopping material before water swelling is large, the fitting resistance of the joint part increases when placing on the ground, or the water-stopping material peels and damages due to friction with the opposing joint part or the ground. Or Therefore, as shown in FIG. 2, a recess 4 is provided in a part of the joint portion 3 to accommodate most of the water blocking material 6. Thereby, the clearance gap between the other side of the joint part 3 and the water stop material 6 before water swelling is increased, and the thickness of the water stop material 6 is increased.

  Next, an example of designing a U-shaped steel sheet pile in which no recess is formed on the inner surface side of the claw bottom portion of the joint portion in a cross-sectional view will be described. The U-shaped steel sheet pile itself has the same structure as that of the steel sheet pile shown in FIG. 1 except that a recess is not formed in the joint portion. FIG. 7 shows a state in which a joint portion of a steel sheet pile in which no depression is formed is fitted. A gap is formed between the inner surface of the claw bottom portion of one joint portion 3 and the outer surface of the claw tip portion 5 of the other joint portion 3. When the fitting state of adjacent steel sheet piles is the most compressed side, a gap of about 10 mm is generated in the joint portions 3 and 3. A water-stopping material 7 made of moisture-curing special polyurethane resin having a volume expansion rate of about 5 times is applied to the inner surface side of the nail bottom portion of the joint portion 3.

  FIG. 8 is a plot of the relationship between the joint clearance and the contact stress of the water stop material when this water stop material is applied. According to FIG. 8, it can be seen that the contact stress generated in the water-stopping material decreases as the gap amount increases. If the gap amount is the same, the contact stress increases as the coating thickness of the water-stopping material increases.

  FIG. 9 is a graph in which the allowable gap amount at which the contact stress of the waterstop material becomes 0.2 MPa is read from this figure and the coating thickness of the waterstop material is plotted on the horizontal axis. From FIG. 9, the relationship between the maximum value of the allowable gap amount that can be stopped when the water pressure difference between both sides of the joint portion is 0.2 MPa, for example, and the coating thickness of the water blocking material is obtained.

  In addition, although the said embodiment demonstrated by the example using the steel sheet pile which has a Larsen joint, in this invention, you may use the steel sheet pile which has not only a steel sheet pile which has a Larsen joint but a linear joint.

Sectional drawing of a steel sheet pile. Sectional drawing of a pair of fitting part made to fit. The schematic diagram which shows the principle of water stop. FIG. The graph which shows the relationship between the clearance gap between joints, and the contact stress of a water stop material. The graph which shows the relationship between a rubber-seal-material diameter (water-stop material) and the amount of allowable gaps. Sectional drawing of a pair of coupling part in which the hollow is not formed. The graph which shows the relationship between the clearance gap between joints, and the contact stress of a water stop material. The graph which shows the relationship between the application thickness of a water stop material, and the amount of permissible gaps.

Explanation of symbols

3 ... Joint part 6, 7 ... Water stop material gn ... Gap amount gmax ... Maximum gap amount Pw ... Working water pressure (water pressure difference)
σ ... Contact stress

Claims (7)

In the design method of the joint portion of the steel sheet pile for the water-impervious wall that restrains the water-swellable waterproofing material between the joint portions facing each other of the steel sheet pile,
Even when the maximum gap is generated between the joints due to the fitting state of the steel sheet pile, so that the contact stress between the joint part and the water-swellable water stop material after water swelling exceeds the water pressure difference on both sides of the steel sheet pile, A design method for a joint portion of a steel sheet pile for a water shielding wall, wherein the maximum gap between the joint portions, the thickness and the material of the water-swellable waterproofing material are designed.   In the case of using a water-swelling water-stopping material of a predetermined thickness and material, the relationship between the gap between the joints and the contact stress between the joint and the water-swelling water-stopping material after water swelling is obtained in advance. The design method of the joint part of the steel sheet pile for a water shielding wall according to claim 1, wherein the maximum gap between the joints, the thickness and the material of the water blocking material are designed based on this relationship.   By providing a recess in which one side of the joint portion accommodates the water-swellable water-stopping material, the gap between the other side of the joint portion and the water-swellable water-stopping material before water swelling is increased, and the water-swellable water-stopping material The design method of the joint part of the steel sheet pile for impermeable walls according to claim 1 or 2, wherein the thickness of the steel sheet pile is increased.   The cross-sectional shape of the water-swelling water-stopping material before water swelling is set to a substantially circular shape with a diameter of 8 to 18 mm, and the amount of protrusion from one of the joint portions of the water-swelling water-stopping material before water swelling is It sets to 1-2 mm, The design method of the coupling part of the steel sheet pile for water-shielding walls of Claim 3 characterized by the above-mentioned. In the joint part structure of the steel sheet pile for the impermeable wall that restrains the water-swellable water-stopping material between the joint parts facing each other of the steel sheet pile,
The contact stress between the joint and the water-swellable water-swelling material after water swelling exceeds the water pressure difference on both sides of the steel sheet pile even when the maximum gap is generated between the joints due to the fitting state of the steel sheet piles. The joint part structure of the steel sheet pile for impermeable walls.   6. A joint structure for a steel sheet pile for a water shielding wall according to claim 5, wherein a recess for accommodating a water-swellable water-stopping material is formed in one of the joint portions facing each other.   The cross-sectional shape of the water-swellable water-stopping material before water swelling is set to a substantially circular shape having a diameter of 8 to 18 mm, and the amount of protrusion of the water-swellable water-stopping material before water swelling from one of the joint portions Is set to 1-2 mm, The joint part structure of the steel sheet pile for water shielding walls of Claim 6 characterized by the above-mentioned.

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