JP2008256523A - Form and form unit for shotcrete specimen, and method of manufacturing shotcrete specimen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a form and a form unit for a shotcrete specimen and a method of manufacturing the shotcrete specimen capable of reducing extremely dispersion of the quality of each specimen when manufacturing a plurality of shotcrete specimens, and executing a compression test capable of measuring its strength characteristic and deformation characteristic. <P>SOLUTION: The form unit 10 for the shotcrete specimen is constituted by mounting and fixing onto a mounting pedestal 4, two or more cylindrical forms 1, etc., made of a resin wherein a net material 3 is mounted on one open end face and a plurality of holes 11, etc., are formed on the cylindrical side face. Flanges 2, 2 are fixed on both ends of the form 1, and the positioning attitude of the form 1 is secured thereby. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a formwork unit for producing a test specimen for shotcrete used for lining an exposed surface of an excavation tunnel and a method for producing the concrete test specimen.

  Generally, in tunnel excavation work by the mountain method, concrete is sprayed on the surface of the tunnel bedrock being excavated and lining is performed to stabilize the natural ground. When spraying concrete, spray concrete made by adding quick setting agent to ready-mixed concrete is used, and it hardens at an early stage after spraying to protect the exposed surface of the rock mass and to displace the shaft inside the liner by natural ground displacement. Force is generated to suppress deformation of the tunnel cross section.

  In order to perform applicability and economic design of this shotcrete due to the action of such shotcrete, it is extremely important to grasp the strength and deformation characteristics with high accuracy immediately after spraying on the rock surface. This is particularly important for young ages up to one day, where most of the deformation from the natural ground accompanying tunnel excavation is received.

  In order to realize the above-mentioned action, the sprayed concrete is generally designed to solidify within a few minutes and exhibit the effect of supporting the tunnel cross section within about 24 hours. It is not easy to continuously measure and evaluate physical properties and properties of the shotcrete in a short time.

  In particular, when producing a test specimen for shotcrete, the fluidity usually disappears within a few minutes due to the effect of the quick setting agent, and the formability to a mold or the like becomes difficult. Therefore, there is a big problem that it is extremely difficult to manufacture several to dozens of test specimens with little variation in quality. Because of this problem, in materials up to the age of 1 day, a method of measuring the strength by compressing a cylindrical specimen such as a general concrete test has not been implemented.

  The test method for shotcrete is generally to manage the strength for several hours to 24 hours after the concrete is sprayed. Specifically, concrete produced by spraying on a formwork of a predetermined shape is drawn into a cone shape. The method of estimating the strength from the pulling resistance value at the time (Spray concrete guideline (repair and reinforcement) JSCE-G 561-2005, see the same explanation), the penetration amount and penetration resistance value when piercing needle-shaped objects The method of estimating strength from the method (spreading concrete guideline (repair / reinforcement) JSCE-G 562-2005, see the same description) is used.

  Furthermore, in patent document 1, the elastic wave velocity during hardening of shotcrete is measured at any time, and at the time of each measurement, the above-mentioned pull-out test (pull-out test) is performed to obtain the relationship between the elastic wave velocity and the pull-out test value. In addition, based on this result, a technique for estimating a hardening state at an arbitrary time after spraying of shotcrete at each site is disclosed.

JP 2000-55895 A

  In the tunnel construction method disclosed in Patent Document 1 described above, by measuring the elastic wave velocity of shotcrete, the current hardening state is immediately grasped from the already created table relating to the elastic wave velocity-hardening state. It becomes possible to do.

  However, the creation of the table relating to the elastic wave velocity-hardening state is based on the above-mentioned pull-out test (pull-out test), and is not based on the uniaxial compression test as in the case of a general concrete specimen. Is still not evaluated. Furthermore, although there are few errors in the elastic wave velocity measurement itself, it is only possible to estimate the intensity indirectly from the correlation with the measured elastic wave velocity when determining the relationship with the intensity, and the intensity evaluation results vary. The occurrence of this is undeniable.

  The present invention has been made in view of the above-mentioned problems, and when producing a plurality of shotcrete test specimens, it is possible to extremely reduce the variation in the quality of each test specimen. Formwork and formwork unit for shotcrete specimens that can be subjected to a compression test that can measure its strength and deformation characteristics as well as tests using the body, and An object is to provide a method for producing a shotcrete specimen.

  In order to achieve the above object, a formwork for a shotcrete test specimen according to the present invention is a formwork for producing a shotcrete test specimen, which is made of resin and has a cylindrical shape, and an open end face thereof. In addition, a perforated member in which a plurality of holes having a size smaller than the maximum particle size of the aggregate in the shotcrete is formed is mounted, and a plurality of holes are formed in the cylindrical side surface. It is a feature.

  Here, shotcrete is a mixture of cement, aggregate, and water with a quick setting agent such as a quick setting cement mineral or calcium sulfoaluminate mineral. The specifications and the mixing ratio thereof are blended and adjusted depending on the desired strength, strength development rate, and the like.

  The mold of the present invention is made of resin and has a cylindrical shape. A net member is attached to one open end surface of the mold and a plurality of holes are formed on the cylindrical side surface.

  Here, “made of resin” means a general resin such as a synthetic resin such as a natural resin or plastic, and also means to exclude a steel material having a high hardness. This is because the mold can be easily removed from the mold by making the mold from a relatively soft material such as plastic. For example, when removing a formwork, by cutting the plastic moldwork with a cutter (demolding in a vertically split state such as half), an excessive external pressure is applied to the shotcrete specimen during curing. The problem of demolding such as giving or damaging can be solved. This is because shotcrete can be demolded immediately after spraying by the action of the quick setting agent, and the specimen is self-supporting, but its strength is still low immediately after spraying. This is because if it is subjected to an impact such as bending, twisting or striking, it can be easily destroyed or damaged, so that it is necessary to realize demolding as quietly and promptly as possible. Since such demolding can be realized, it is possible to perform a compression test from a young age.

  In addition, the mold is made of resin as described above, has a cylindrical shape such as a cylindrical shape, and a plurality of holes are formed in the cylindrical side surface, and a plastic mesh is formed at one end of the cylindrical body. Alternatively, a perforated member such as a net member made of a wire net is mounted. Here, the aggregate in the shotcrete is prevented from going out of the hole of the perforated member, and the aggregate partially surrounds the hole so that the air is released to the outside and enters the mold. In order to achieve the effect of filling with shotcrete, it is desirable that the hole size of the perforated member be smaller than the maximum particle size of the aggregate. Similarly, the size of the hole formed in the cylindrical side surface is preferably set to a size smaller than the maximum particle size of the aggregate.

  Here, in a general cylindrical steel formwork, when the concrete is sprayed from one open end, the air entrapped in the formwork does not come out of the formwork, and as a result, a large number of air enters the test body. Voids are formed. According to the formwork used in the manufacturing method of the present invention, a large number of holes are formed on the side surface, and a perforated member for air bleeding is formed on the end surface opposite to the side on which the concrete is sprayed. By doing so, the problem that voids are formed in the test body is solved.

  A formwork unit for a shotcrete specimen according to the present invention is a formwork unit for producing a shotcrete test specimen, which is made of resin and has a cylindrical shape, and is sprayed on one open end surface thereof. A perforated member having a hole having a size smaller than the maximum particle size of the aggregate in the concrete is mounted, and two or more molds formed with a plurality of holes on the cylindrical side surface are attached to the mounting frame. It is characterized by being attached and fixed to.

  The formwork unit of the present invention is a formwork unit in which two or more of the above-mentioned formwork are attached and fixed to a mounting base, and a plurality of test bodies are manufactured by one spraying.

  Here, the perforated member constituting each mold may be mounted for each mold, or one long perforated member is mounted so as to cover the open end surfaces of all the molds. Also good.

  In a preferred embodiment of a formwork unit for a shotcrete test specimen according to the present invention, first and second flanges projecting outward from the side end portions are formed at both open ends of the formwork. The mounting frame includes a first locking member for locking a first flange formed on the one end surface side of the mold, and a first locking member formed on the other end surface side of the mold. A second locking member for locking the two flanges, the first locking member and the second locking member are formed in parallel to each other, and each mold is By fixing the first and second flanges in a posture in which the first and second flanges are locked to the first and second locking members, the axial direction of each mold is positioned in parallel.

  In the test of shotcrete, it is necessary to prepare a large number of specimens for one test and evaluate the material properties as in the case of using general concrete. Here, in order to manufacture test pieces with little variation in quality at once (continuously), the molds are placed in parallel with each other so that the axial direction of the mold is the direction of sprayed concrete. It needs to be fixed. Therefore, by providing engaging flanges parallel to each other at both ends of the mold, and locking the respective engaging flanges with the two locking members parallel to each other constituting the mounting base, the axis of each mold Are fixed in a posture oriented in the same direction. In this case, it is preferable that the spray nozzle of the shotcrete is configured to be able to move at any time between both ends of the formwork unit. That is, after spraying a specific amount of shotcrete into one mold, the nozzle moves automatically (or the mold unit moves) to the axial center position of adjacent molds, and blows in the same way. It is a form in which the spraying of artificial concrete is executed.

  Further, the method for producing a shotcrete specimen according to the present invention is a method for producing a shotcrete specimen, which is made of resin and has a cylindrical shape, and an open end surface thereof is provided in the shotcrete. A perforated member in which a plurality of holes having a size smaller than the maximum particle size of the aggregate is formed is attached, and two or more molds in which a plurality of holes are formed in the cylindrical side surface are attached. A first step of preparing a formwork unit that is fixedly attached to a gantry, and spray concrete is sprayed from the other end surface side of the formwork that has been opened. And a second step of manufacturing a body.

  This manufacturing method is a method for manufacturing a plurality of test bodies at once without any variation in quality by using the formwork unit described above.

  Here, preferably, the demolding in the second step is performed by cutting the two positions of the mold in the height direction of the mold. As described above, this can be realized by molding each of the molds constituting the mold unit with a resin material such as plastic having a hardness capable of cutting with a cutter. Problems such as damage to the specimen can be effectively solved.

  Further, preferably, in the second step, the both ends of the test body before strength development is removed, and the molds are removed after the both ends are treated with a rapid hardening material.

  The formwork used is provided with a perforated member such as a mesh material at the bottom, and air can escape through this perforated member, but it is still possible to avoid the shotcrete reflecting off the perforated member. However, compared with the general part of the formwork, the rebound pool of the shotcrete is generated on the side surface near the bottom part, and the end surface processing (flat finishing) is required. Therefore, before the shotcrete is hardened, both ends of the specimen that has not yet been cured are scraped off, and the scraped portion is filled with a rapid hardening material, and both ends are capped with a plate material to cure the specimen. It is good. Here, since this board | plate material is capped by the 1st, 2nd flange surface which has a mutually parallel relationship, it does not require any flat finishing processing with respect to the test body after hardening. According to such a manufacturing method, it is possible to reduce the cost of the test by eliminating the need for finishing the end face of the test body.

  After the specimen is manufactured by the above manufacturing method, the specific gravity is obtained by measuring the volume and weight of each specimen. By not using a specimen having a specific gravity outside the allowable range by a known statistical method in the compression test, the test accuracy can be further increased.

  As can be understood from the above description, according to the formwork for the shotcrete test body of the present invention, the test for homogeneous shotcrete that does not produce voids that significantly affect the strength characteristics and deformation characteristics. The body can be manufactured. Moreover, according to the formwork unit and the manufacturing method for the shotcrete test specimen according to the present invention, a plurality of test specimens having no quality variation can be obtained at any time between several hours to about 24 hours after spraying. Can be produced at once. Therefore, it is possible to perform a compression test on the shotcrete specimen, and it is possible to evaluate deformation characteristics such as Young's modulus and creep characteristics in addition to the strength characteristics.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a mold and a net constituting the mold unit of the present invention, and FIG. 2 is a longitudinal sectional view of an embodiment of the mold unit of the present invention. FIG. 3 is a longitudinal sectional view showing a state in which both ends of the test body are cut off before the test body in the mold is still cured, and FIG. 4 is a case where the hardened material is filled in the area cut in FIG. And is a longitudinal sectional view showing a state where the surface is capped. FIG. 5 is a perspective view showing a situation in which two portions of the formwork are cut with a cutter.

  As shown in FIG. 1, the mold 1 of the present invention has a cylindrical shape having a hollow portion corresponding to a test body having a desired size and shape, and a large number of holes 11,. Further, the mold 1 is molded from a plastic material and can be easily cut with a cutter or the like as will be described later.

  Further, flanges 2 and 2 are fixed to one end 12 and the other end 13 that define the open end face of the mold 1. The flange 2 is also molded from the same material as the mold 1 and may be retrofitted to the mold 1 with an adhesive or the like, or may be molded integrally with the mold 1.

  Sprayed concrete is sprayed from a spray nozzle (not shown) from one end 12 side of the mold 1, and the net member 3 is directly or indirectly from the other end 13 side as illustrated. Provided.

  FIG. 2 shows a mold unit 10 including a plurality of molds 1 shown in FIG. In the illustrated embodiment, plate-like vertical members 43, 43 are connected to each other by plate-like horizontal members (locking members 41, 42) at the top and bottom, and the lower surface of the locking member 42 is supported by pedestals 44, 44. The form frame 1 is placed and fixed through the mounting base 4 and the attachment holes 41a formed in the locking member 41, thereby forming the form unit 10. Here, each mold 1 is placed parallel to the vertical member 43 by the flanges 2 and 2 at both ends being locked by the locking members 41 and 42. ,... Are attached to the mounting base 4 with their respective axes being parallel.

  FIG. 2 also shows a situation where spray concrete is sprayed from the spray nozzle 5 to one mold 1. As shown in the figure, when sprayed concrete is sprayed (X1 direction), the air is released to the outside of the mold 1 through the holes 11 of the mold 1 (X2 direction), and the other end 13 side. Then, the air can be released to the outside through the escape hole 42 a formed in the locking member 42 and the net member 3.

  After the spraying of sprayed concrete to one mold 1 is completed, the spray nozzle 5 moves automatically or manually to the adjacent mold 1 (Y direction) and sprays the sprayed concrete in the same way. Start.

  Thus, no air pool remains in the mold 1, the axes of the molds 1,... Are in a parallel relationship, and the spraying direction of the spray nozzle 5 is the axial direction. By spraying the shotcrete, it is possible to produce a plurality of test specimens having no gaps and no quality variation (or very little). In the embodiment shown in the figure, three molds 1, 1, 1 are mounted on the mounting base 4, but a form in which four or more molds 1,. Of course.

  FIG. 3 shows that after the shot concrete is sprayed into the mold 1 and an uncured specimen is manufactured, both ends of the shot concrete are removed and the removal regions R and R are formed at a stage where the shot concrete is not yet cured. It shows the state of formation (here, the general part S1 of the specimen is formed).

  By removing both ends, aggregates and the like protruding outward from both flanges 2 and 2 are also removed. Here, the height of the removal region R is, for example, about 5 mm when the total height of the specimen is about 20 cm. In addition, the removal work takes about 1 hour after spraying shotcrete.

  Next, the process proceeds to FIG. 4, and the removal region R is filled with a suitable rapid-hardening material to form the end S <b> 2 of the test body, and the surface of the flanges 2 and 2 is leveled with a glass plate 6 or the like. Try capping. The specimen S is formed when both the end portion S2 made of the rapid-hardening material and the general portion S1 made of shotcrete exhibit a predetermined strength. Here, the predetermined strength expression means the strength of a specimen prepared for executing a compression test at an appropriate time passage within a time range of several hours to about 24 hours after spraying. is there.

  By performing this end surface treatment when the test body S is uncured and capping the end surface as described above, it is possible to save processing time for performing the end surface treatment on the cured test body, and the test cost is greatly increased. Reduction can be achieved.

  FIG. 5 is a diagram illustrating a situation where the mold 1 is removed after a predetermined time has elapsed. In the demolding method, at two locations on the mold 1 made of plastic, usually two corresponding locations on a diagonal line, the cutter 1 cuts C1 and C2 in the mold 1 in the height direction of the mold 1 Done in the way. When the cutting at two places is completed, the mold can be removed without applying an impact or an external pressure to the test body S by gently removing the half-shaped mold form from the test body S.

  Such a demolding operation is because the mold 1 is formed of plastic that can be easily cut by the cutter C.

  The demolding method described above is particularly effective when demolding is performed at the initial strength development stage of shotcrete after a few hours have elapsed since spraying. When this shotcrete test specimen is manufactured with a conventional steel formwork, such demolding cannot be carried out, so impact and external pressure on the test specimen during demolding will always occur. Demolding that did not damage the specimen at a stage where the strength was not sufficiently developed was almost impossible.

  After removing the mold 1 by the above method, the volume and weight of the specimen S are measured to determine the specific gravity, and those having a specific gravity outside the allowable range are excluded from the test object.

  A compression test is performed on the specimen S having an appropriate specific gravity, and deformation characteristics such as compression strength, Young's modulus, and creep are measured.

  By producing a specimen for shotcrete using a mold unit 10 having a plurality of molds 1 described above, it is possible to produce a plurality of shotcrete specimens at once without any quality variation. Become. In addition, the ability to produce test specimens with no variation in quality makes it possible to subject this specimen to a compression test in the same way as ordinary concrete specimens, and to provide both strength and deformation characteristics of young specimens. It becomes possible to evaluate with high accuracy. Appropriate evaluation of both strength characteristics and deformation characteristics leads to an evaluation of the support effect of shotcrete in a form that is in line with the actual behavior of the support members.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

It is the perspective view which showed one Embodiment of the formwork and net | network material which comprise the formwork unit of this invention. It is a longitudinal section of one embodiment of a formwork unit of the present invention. It is the longitudinal cross-sectional view which showed the state by which the both ends of the test body were shaved before the test body in a formwork still hardened | cured. FIG. 4 is a longitudinal sectional view showing a state where the hardened material is filled in the region cut in FIG. 3 and the surface thereof is capped. It is the perspective view which showed the condition which has cut | disconnected two places of a formwork with the cutter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Formwork, 11 ... Hole, 12 ... One end, 13 ... Other end, 2 ... Flange, 3 ... Net material (perforated member), 4 ... Mounting stand, 41, 42 ... Locking member, 43 ... Vertical member, 44 ... pedestal, 5 ... spray nozzle, 6 ... glass plate, 10 ... formwork unit, S1 ... general part of test body, S2 ... end of test body, S ... test body

Claims (6)

A formwork for producing shotcrete specimens,
It is made of resin and has a cylindrical shape. A perforated member in which a plurality of holes having a size smaller than the maximum particle diameter of the aggregate in the shotcrete is formed is attached to the opened one end surface, and the cylindrical shape Formwork for shotcrete test specimens, which has a plurality of holes formed on the sides. A formwork unit for producing shotcrete specimens,
It is made of resin and has a cylindrical shape. A perforated member having a hole having a size smaller than the maximum particle size of the aggregate in the shotcrete is attached to the open one end surface, and a plurality of holes are attached to the cylindrical side surface. A formwork unit for a shotcrete specimen, wherein two or more formwork formed with holes are fixedly attached to a mounting base. First and second flanges projecting outward from the side end portions are formed at both open ends of the mold,
The mounting frame includes a first locking member for locking a first flange formed on the one end face side of the mold and a second flange formed on the other end face side of the mold. A second locking member for locking is provided,
The first locking member and the second locking member are formed in parallel to each other,
Each mold is fixed in a posture in which the first and second flanges are locked to the first and second locking members, whereby the axial direction of each mold is positioned in parallel. A formwork unit for a shotcrete test specimen according to claim 2. A method for producing a shotcrete specimen,
It is made of resin and has a cylindrical shape. A perforated member in which a plurality of holes having a size smaller than the maximum particle diameter of the aggregate in the shotcrete is formed is attached to the opened one end surface, and the cylindrical shape A first step of preparing a mold unit in which two or more molds, each having a plurality of holes formed on a side surface thereof, are mounted and fixed to a mounting base;
A second step of spraying shotcrete from the opened other end side of the mold, demolding after waiting for a predetermined strength expression, and producing a columnar specimen;
A method for producing shotcrete specimens consisting of   The method for producing a shotcrete specimen according to claim 4, wherein the demolding in the second step is performed by separating the mold in the height direction of the mold.   6. The blowing according to claim 4 or 5, wherein in the second step, both end portions of the test body before strength development are removed and the both end portions are treated with a rapid hardening material, and then demolding is performed. A method for producing a cemented concrete specimen.

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