Rock crushing tool and fracturing method using the same

Abstract

To introduce cracks in a wide range against an area to be fractured from a borehole toward a free surface.SOLUTION: A fourth tip of a wedge member is inserted into a fourth internal space formed between a first blade member and a third blade member inserted into a borehole. The fourth tip has a first sliding surface, a second sliding surface, and a third sliding surface that can slide against the first blade member, a second blade member, and the third blade member, respectively, and has a tapered shape such that the second sliding surface and the third sliding surface slope toward the first sliding surface as advancing in a borehole formation direction. As the wedge member moves along the borehole in the borehole formation direction, the second blade member moves in a second direction while sliding against the second sliding surface of the wedge member, and presses against an inner wall of the borehole. Simultaneously, the third blade member moves in a third direction while sliding against the third sliding surface of the wedge member, and presses against the inner wall of the borehole. By pressing an inner wall surface of the borehole on a free surface side from two different directions in this manner, cracks are introduced into an area to be fractured from the borehole toward the free surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a rock-breaking tool for breaking up rock mass, boulders, concrete structures, and other objects to be crushed, and to a crushing technique for crushing the object using the tool. In particular, it relates to a technique for crushing the object by introducing a crack into the crushed area from a drilled hole formed near the free surface of the object toward the free surface. [Background technology]

[0002] As a crushing method for efficiently crushing a crushable object having a free surface, the applicant of the present application has implemented a method in which multiple holes are drilled in a row near the free surface of the object to be crushed so that they are parallel to the free surface, and then, for each hole, a rock-breaking tool described in Patent Documents 1 to 3 is used to create cracks in the area to be crushed from the drilled hole toward the free surface, thereby crushing the object (Non-Patent Document 1).

[0003] The rock-breaking tool combines a wedge member (arrow) and two blade members (blades) within a drilled hole. The tip of one blade member is inserted into the internal space opposite the free surface of the drilled hole, and the tip of the other blade member is inserted into the internal space opposite the free surface. The tip of the wedge member is slidably inserted between these blade members. Then, by striking the rear end of the wedge member with a breaker to press the wedge member, the two blade members slide relative to the inclined surface formed at the tip of the wedge member and move radially outward of the drilled hole. At this time, the blade members press against the inner wall of the drilled hole, breaking up the rock in the area to be crushed. In this way, the area to be crushed within the object to be crushed is crushed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5857375 [Patent Document 2] Patent No. 6387505 [Patent Document 3] Patent No. 6464396 [Non-patent literature]

[0005] [Non-Patent Document 1] "Super Kusabi-kun", Kamishimagumi homepage, [online], [searched on April 1, 2024], Internet<URL:http: / / kamishimagumi.co.jp / technique / kusabikun / kusabikun.htm> Summary of the Invention [Problem to be solved by the invention]

[0006] Of the two blade members, the blade member on the free surface side moves in one direction from the central axis of the wedge member toward the free surface (corresponding to the (+Y) direction in the drawings described later), applying a pressing force to the inner wall surface of the drilled hole. Therefore, the range in which cracks are introduced is relatively narrow in the depth direction of the drilled hole (corresponding to the (Z) direction in the drawings described later) and the width direction (corresponding to the (X) direction in the drawings described later), which is perpendicular to both of the above-mentioned one direction. For this reason, it is necessary to set the spacing between the drilled holes relatively narrow. Therefore, in order to improve the efficiency of the crushing operation, a rock-breaking tool is desired that can expand the range in which cracks are introduced in the row direction of the drilled holes, that is, in the width direction.

[0007] This invention has been made in consideration of the above-mentioned problems, and aims to provide a rock-breaking tool that can introduce cracks over a wide area in the crushed area from the drilled hole toward the free surface, and a crushing method using said tool. [Means for solving the problem]

[0008] A first aspect of this invention is a rock breaking tool that introduces cracks in a crushed area from a drilled hole that has been pre-formed in the object to be crushed in the direction of drilling in the vicinity of the free surface of the object to be crushed toward the free surface, and that includes: a first blade member having a first tip portion that can be inserted and removed into a first internal space located on the opposite side of the free surface of the drilled hole; a second blade member having a second tip portion that can be inserted and removed into a second internal space located on the free surface side of the drilled hole, parallel to the free surface, and on one side of the first direction perpendicular to the drilling direction; a third blade member having a third tip portion that can be inserted and removed into a third internal space located on the free surface side of the drilled hole, parallel to the free surface, and on the other side of the first direction; and a wedge member having a fourth tip portion that can be inserted and removed into a fourth internal space sandwiched between the first tip portion, the second tip portion, and the third tip portion of the drilled hole. The fourth tip portion has a first sliding surface, a second sliding surface, and a third sliding surface that can slide on the first blade member, the second blade member, and the third blade member, respectively, and has a tapered shape such that the second sliding surface and the third sliding surface slope toward the first sliding surface as it progresses in the hole-forming direction, and when viewing the hole-forming from the opposite side of the hole-forming direction, with respect to an imaginary line that passes through the central axis of the wedge member and is perpendicular to the free surface, the direction that slopes to one side of the first direction is defined as the second direction, and the direction that slopes to the other side of the first direction is defined as the third direction, as the wedge member moves in the hole-forming direction along the hole-forming direction, the second blade member moves in the second direction while sliding against the second sliding surface of the wedge member, pressing against the inner wall of the hole, and the third blade member moves in the third direction while sliding against the third sliding surface of the wedge member, pressing against the inner wall of the hole.

[0009] In addition, a second aspect of the present invention is a crushing method for crushing a crushable area from a pre-formed drilled hole in the direction of drilling the object toward the free surface near the free surface of the object to be crushed, characterized by comprising the steps of: preparing the rock-breaking tool; inserting the first tip of the first blade member, the second tip of the second blade member, the third tip of the third blade member, and the fourth tip of the wedge member into the first internal space, the second internal space, the third internal space, and the fourth internal space of the drilled hole, respectively; and applying an external force to the rear end of the wedge member while keeping the first sliding surface, the second sliding surface, and the third sliding surface in sliding contact with the first tip of the first blade member, the second tip of the second blade member, and the third tip of the third blade member, respectively, thereby pressing the second tip of the second blade member and the third tip of the third blade member against the inner wall of the drilled hole to break the rock. [Effects of the Invention]

[0010] As described above, according to the present invention, as the wedge member moves in the direction of drilling, the second blade member moves in the second direction to press against the inner wall of the drilled hole, and the third blade member moves in the third direction to press against the inner wall of the drilled hole. In this way, by pressing against the inner wall surface of the drilled hole on the free face side from two different directions (= second direction + third direction), cracks are introduced into the crushed area from the drilled hole toward the free face. Therefore, cracks can be introduced over a wide area in the crushed area, resulting in improved rock breaking efficiency and crushing efficiency. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a rock breaking tool and a breaker used when carrying out an embodiment of the breaking method according to the present invention. FIG. [Figure 2] 1 is a perspective view showing the configuration of a rock breaking tool used when carrying out an embodiment of a breaking method according to the present invention. FIG. [Figure 3] 3A and 3B are diagrams showing the configuration of the tip end of a wedge member and a blade member in the first embodiment of the rock breaking tool according to the present invention. [Figure 4]10A and 10B are diagrams showing the configuration of the tip portions of the wedge member and the blade member in a second embodiment of the rock breaking tool according to the present invention. [Figure 5] FIG. 10 is a perspective view showing the configuration of a third embodiment of a rock splitting tool according to the present invention. [Figure 6] 10A and 10B are diagrams showing the configuration of the tip portions of the wedge member and the blade member in a third embodiment of the rock breaking tool according to the present invention. [Figure 7] FIG. 10 is a perspective view showing the configuration of a fourth embodiment of a rock splitting tool according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 illustrates a rock-breaking tool and a breaker used in carrying out one embodiment of the rock-breaking method of the present invention. The rock-breaking tool 1 has three blade members 11-13 and a wedge member 14 whose tip is removably inserted between the blade members 11-13. In this specification, the direction Z in which a drilled hole 21 is formed in the object to be crushed 2 is referred to as the "hole-forming direction." Furthermore, the direction parallel to the free surface 22 of the object to be crushed 2 and perpendicular to the hole-forming direction Z is referred to as the "first direction X." One side of this first direction X is referred to as the "+X direction" and the other side is referred to as the "-X direction," respectively. Furthermore, the direction perpendicular to both the hole-forming direction Z and the first direction X, i.e., the direction from the drilled hole 21 toward the free surface 22, is referred to as the "free surface direction (+Y)," and the direction opposite the free surface 22 is referred to as the "anti-free surface direction (-Y)."

[0013] 1 includes a partially enlarged view of the vicinity of the opening of drilling hole 21 as viewed from the opposite side of the drilling direction Z. As shown in this partially enlarged view, drilling hole 21 has four internal spaces. Specifically, drilling hole 21 has a first internal space 211 located on the opposite side of free surface 22, i.e., on the anti-free surface direction (-Y) side; a second internal space 212 located on the free surface direction (+Y) side of first internal space 211 and on one side in first direction X, i.e., the (+X) direction side; and a third internal space 213 located on the free surface direction (+Y) side of first internal space 211 and on the other side in first direction X, i.e., the (-X) direction side. Tips 11a to 13a of blade members 11 to 13 are removably inserted into these three internal spaces 211 to 213, respectively. The space in drilling hole 21 sandwiched between inserted tip portions 11a to 13a corresponds to fourth internal space 214, and tip portion 14a of wedge member 14 can be inserted into and removed from fourth internal space 214.

[0014] FIG. 2 is a perspective view showing the configuration of a rock-breaking tool used in carrying out one embodiment of the rock-breaking method according to the present invention. FIG. 3 is a diagram showing the configuration of the tips of the wedge and blade members of the rock-breaking tool. The rock-breaking tool 1 shown in these drawings corresponds to the first embodiment of the rock-breaking tool according to the present invention. In FIG. 3, (a) shows the wedge member 14 pushed in the hole-forming direction Z, and (b-1) to (b-4) are cross-sectional views of the wedge member and blade member at different positions in the hole-forming direction Z. In this rock-breaking tool 1, the blade members 12 and 13 have symmetrical shapes with respect to the XZ plane including the imaginary line VL (FIG. 1) that passes through the center axis 14c (FIG. 1) of the wedge member 14 and is perpendicular to the free surface 22. Therefore, following the description of the blade member 11, the configuration of the blade member 12 will be described below. Meanwhile, the components of the blade member 13 will be denoted by corresponding reference numerals and will not be described again.

[0015] The blade member 11 has a flange portion 11b and a tip portion 11a extending from the underside of the flange portion 11b in a direction parallel to the hole-forming direction Z. As shown in Fig. 2, the flange portion 11b has a planar size that is sufficiently larger than the tip portion 11a. More specifically, the flange portion 11b has a planar size that allows it to engage with the periphery of the surface of the hole 21, whereas the tip portion 11a has a planar size that is smaller than the hole 21. This also applies to the blade members 12 and 13, which will be described later.

[0016] The surface of tip 11a that faces the inner wall of drilling hole 21, i.e., the surface on the anti-free surface direction (-Y) side, is basically configured as an arc surface along the hole-forming direction Z, and functions as a pressing surface that presses against the inner wall of drilling hole 21, as described below. Note that the cross section of the arc surface here does not necessarily have to be a part of a circle, and also includes cases where the cross section is a part of an ellipse. Furthermore, tip 11a has an inclined surface formed on the opposite side of the arc surface (pressing surface), i.e., the side facing blade members 12, 13. This inclined surface is finished so that it approaches blade members 12, 13 as it progresses in hole-forming direction Z.

[0017] The blade member 12 has a flange portion 12b and a tip portion 12a extending from the underside of the flange portion 12b in a direction parallel to the hole-forming direction Z. The surface of the tip portion 12a facing the inner wall of the hole 21, i.e., the surface on the free surface direction (+Y), is basically configured as an arc surface along the hole-forming direction Z, and functions as a pressing surface that presses against the inner wall of the hole 21, as described below. In addition, the tip portion 12a has an inclined surface formed on the side opposite the arc surface (pressing surface), i.e., the side facing the blade member 11. This inclined surface is finished so that it approaches the blade member 11 as it progresses in the hole-forming direction Z. The blade member 13 is also configured in the same manner as the blade member 12. However, in the blade members 12 and 13, the arc surfaces of the tip portions 12a and 13 are half the arc surface of the tip portion 11a. During rock breaking, the inclined surfaces of the blade members 12, 13 are positioned opposite the inclined surface of the tip portion 11a, and the tip portions 11a to 13a of the blade members 11 to 13 are inserted into the first internal space 211 to the third internal space 213 of the drilled hole 21, respectively. By inserting the tip portions 11a to 13a of the blade members 11 to 13 into the drilled hole 21 in this manner, a fourth internal space 214 is formed that tapers in the drilling direction Z, more specifically, in the shape of an inverted triangular pyramid.

[0018] A wedge member 14, which is finished in the shape of an inverted triangular pyramid, is press-fitted into this tapered fourth space 214 so as to fit into this fourth space 214. A tip portion 14a of this wedge member 14 has a triangular shape in a cross section perpendicular to the Z direction, and the triangular shape shrinks at a constant rate along a central axis 14c (FIG. 1) of the wedge member 14 toward the tip. More specifically, as shown in FIG. 3, the tip portion 14a has three sliding surfaces 141 to 143 that can slide on the blade members 11 to 13, respectively, and is finished so that the sliding surface 141 inclines toward the free surface and the sliding surfaces 142 and 143 incline toward the sliding surface 141 as they proceed in the hole-forming direction Z. Therefore, as wedge member 14 moves in hole-forming direction Z, blade member 11 slides relative to sliding surface 141 of wedge member 14 without moving its position, pressing the inner wall of drilled hole 21 in the (-Y) direction with blade member 11. Blade member 12 slides against sliding surface 142 of wedge member 14 and moves in second direction D2, pressing the inner wall of drilled hole 21 in the second direction D2, while blade member 13 slides against third sliding surface 143 of wedge member 14 and moves in third direction D3, pressing the inner wall of drilled hole 21 in the third direction D3. Here, second direction D2 refers to the direction inclined by a predetermined angle θ to one side (+X) of first direction X with respect to virtual line VL when drilled hole 21 is viewed from the opposite side of hole-forming direction Z, as shown in the partially enlarged view of FIG. 1. 1, when drilling hole 21 is viewed from the opposite side of drilling direction Z, third direction D3 refers to a direction inclined by a predetermined angle θ toward the other side (-X) of first direction X with respect to imaginary line VL. Note that angle θ corresponds to the settings of sliding surfaces 141-143 provided on wedge member 14 and the inclined surfaces that slide against them. In addition, since this embodiment uses blade members 12 and 13 that have shapes symmetrical with respect to the XZ plane that includes imaginary line VL (FIG. 1), the magnitude of angle θ is the same. However, it goes without saying that the second direction D2 and the third direction D3 may be adjusted by making the shapes different from each other.

[0019] The breaker 3 for pressing in the wedge member 14 is attached to an arm 51 of a construction vehicle 5 such as a hydraulic power shovel via a bracket 52, as shown in Figure 1. This allows the operator to control the position and angle of the arm 51 by operating an operating lever or the like of the construction vehicle 5, thereby controlling the position and attitude of the breaker 3.

[0020] In the rock-breaking tool 1 configured as described above, as shown in FIG. 1, the tips 11a-13a of the blades 11-13 are inserted into the drilled hole 21, and the tip 14a of the wedge 14 is inserted into the fourth internal space 214 surrounded by the inclined surfaces of the blades 11-13. This completes preparation for the rock-breaking process. The piston of the breaker 3 then strikes the rear end of the wedge 14, forcing the tip of the wedge 14 into the drilled hole formation direction Z. As a result, as shown in FIG. 3, the wedge 14 is inserted and moved along the drilled hole 21. Accordingly, the blades 12 and 13 move in the second direction D2 and the third direction D3, respectively, within the drilled hole 21, as indicated by arrows AR2 and AR3 in the figure, pressing against the inner wall of the drilled hole 21. This introduces cracks over a wide area in the first direction X, efficiently breaking the rock in the crushed area R extending from the drilled hole 21 toward the free surface 22. By using the rock breaking tool 1, the efficiency of the crushing method described in Non-Patent Document 1 can be improved.

[0021] In the rock breaking tool 1 configured as described above, the blade member 11 and its tip portion 11a correspond to an example of the "first blade member" and "first tip portion" of the present invention, respectively. The blade member 12 and its tip portion 12a correspond to an example of the "second blade member" and "second tip portion" of the present invention, respectively. The blade member 13 and its tip portion 13a correspond to an example of the "third blade member" and "third tip portion" of the present invention, respectively. The tip portion 14a of the wedge member 14 corresponds to an example of the "fourth tip portion" of the present invention, and its sliding surfaces 141 to 143 correspond to an example of the "first sliding surface," "second sliding surface," and "third sliding surface" of the present invention, respectively.

[0022] The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the wedge member 14 is formed in an inverted triangular pyramid shape, but the shape of the wedge member 14 may also be an inverted triangular pyramid shape.

[0023] In the above embodiment, the sliding surface 141, which corresponds to the "first sliding surface" of the present invention, is an inclined surface that approaches the free surface 22 as it advances in the hole-forming direction Z. However, when the wedge member 14 is pushed in the hole-forming direction Z, the blade member 11 remains in its position, while the blade members 12 and 13 move toward the free surface 22. Therefore, as shown in FIG. 4, the sliding surface 141 may be finished into a plane parallel to the hole-forming direction Z (second embodiment of the rock splitting tool). This also applies to the third embodiment described later.

[0024] Furthermore, in the above-mentioned rock breaking tool 1, the sliding surfaces 141 to 143 are connected to each other, and the tip 14a of the wedge member 14 is finished in a triangular pyramid shape or a truncated triangular pyramid shape, but the shape of the tip 14a of the wedge member 14 is not limited to this, and the sliding surface 142 and the third sliding surface 143 may be finished in a tapered shape that slopes toward the sliding surface 141 as they proceed in the hole drilling direction Z (third embodiment).

[0025] FIG. 5 is a perspective view showing the configuration of a third embodiment of the rock breaking tool according to the present invention. FIG. 6 is a diagram showing the configuration of the tips of the wedge members and blade members of the rock breaking tool shown in FIG. 5. The rock breaking tool 1 according to the third embodiment differs from the rock breaking tools described in Patent Documents 1 to 3 (hereinafter referred to as "conventional tools") in the following two respects. First, as in the first and second embodiments, it is provided with three blade members 11 to 13. Furthermore, in order to move the blade members 12 and 13 in the second direction D2 and the third direction D3, respectively, as the wedge member 14 is pressed into the hole-forming direction Z, sliding surfaces 142 and 143 are provided on the wedge members employed in the rock breaking tools described in Patent Documents 1 to 3. The other configurations are basically the same as those of the conventional tools.

[0026] In the third embodiment, which has these structural differences, as shown by arrows AR2 and AR3 in Figure 6, as the wedge member 14 moves in the drilling direction Z along the drilled hole 21, the blade member 12 slides against the sliding surface 142 of the wedge member 14 and moves in the second direction D2, pressing against the inner wall of the drilled hole 21, while the blade member 13 slides against the sliding surface 143 of the wedge member 14 and moves in the third direction D3, pressing against the inner wall of the drilled hole 21. As a result, as in the first and second embodiments, cracks are introduced over a wide area in the first direction X, efficiently breaking the rock in the crushed region R extending from the drilled hole 21 toward the free surface 22. Using the rock-breaking tool 1 described above can improve the efficiency of the crushing method described in Non-Patent Document 1.

[0027] Furthermore, in the above-described embodiment, the three blade members 11 to 13 are independent of one another, but as shown in FIG. 7, for example, the blade members 11 to 13 may be connected to one another by a connecting mechanism 15, as in Patent Documents 1 to 3. More specifically, the blade members 12 and 13 may be connected to the blade member 11 by spring members 151 and 152, respectively, and the blade members 12 and 13 may be connected to one another by a spring member 153 (fourth embodiment). Note that in the rock splitting tool 1 shown in FIG. 7, the spring members 151 to 153 are configured as a single stage, as in the conventional tools described in Patent Documents 1 and 3, but they may also be connected by an upper and lower two-stage spring member configuration, as in the conventional tool described in Patent Document 2. More specifically, blade member 12 may be interconnected with blade member 11 by two spring members 151 arranged above and below in the hole-making direction Z, blade member 13 may be interconnected by two spring members 152 arranged above and below in the hole-making direction Z, and blade members 12 and 13 may be interconnected by two spring members 153 arranged above and below in the hole-making direction Z.

[0028] In the above embodiment, the piston of the breaker 3 strikes the rear end of the wedge member 14 to apply an external force (white arrows in Figures 3, 4, and 6) to the rear end of the wedge member 14 and move it in the hole-forming direction Z, but the means for applying the external force is not limited to this and, for example, a hydraulic cylinder can be used. In other words, the wedge member 14 may be configured to be pressed in the hole-forming direction Z by a hydraulic cylinder.

[0029] Furthermore, in the above embodiment, the first blade member 11 is placed in the first internal space 211, while two blade members 12 and 13 are placed on the free surface side of the first internal space 211 in the drilling hole 21, i.e., on the (+Y) direction side, but it is also possible to place three or more blade members on the free surface side of the first internal space 211 and press the tip 141 of the wedge member 14 into a fourth internal space surrounded by all of the blade members, so that the blade members on the free surface side move in different directions and press against the inner wall of the drilling hole 21. For example, it is also possible to add another blade member between the blade members 12 and 13, and press the tip 141 to move the blade members 12 and 13 and the other blade member in the second direction D2, the third direction D3, and the (+Y) direction, respectively, to introduce a crack into the crushed region R. [Industrial Applicability]

[0030] The present invention can be applied to all rock-breaking tools for breaking up objects to be crushed, such as bedrock, boulders, and concrete structures, and to all crushing techniques for crushing objects to be crushed using such tools. [Explanation of symbols]

[0031] 1...Rock splitting tool 2...Object to be crushed 11...(first) blade member 11a...(1st) tip part 12...(Second) blade member 12a...(2nd) tip 13...(Third) blade member 13a...(3rd) tip 14...Wedge member 21...Drilling 22…Free surface 141...(first) sliding surface 142...(Second) sliding surface 143...(3rd) sliding surface 211…First internal space 212…Second internal space 213…Third internal space 214...Fourth internal space D2…Second direction D3…Third direction R…Area to be crushed VL...Virtual line X…first direction Z…Drilling direction

Claims

1. A rock breaking tool that introduces cracks in a crushed area from a drilled hole that has been previously formed in the crushed object in the direction of drilling in the vicinity of the free surface of the object to be crushed toward the free surface, a first blade member having a first tip portion removably inserted into a first internal space located on the opposite side of the free surface of the drilled hole; a second blade member having a second tip portion that is insertable into and detachable from a second internal space of the hole, the second internal space being closer to the free surface than the first internal space, parallel to the free surface, and located on one side of a first direction perpendicular to the hole forming direction; a third blade member having a third tip portion that is insertable into and detachable from a third internal space that is located on the free surface side of the first internal space and on the other side in the first direction of the drilled hole; a wedge member having a fourth tip portion that is insertable into and detachable from a fourth internal space of the hole that is sandwiched between the first tip portion, the second tip portion, and the third tip portion, the fourth tip portion has a first sliding surface, a second sliding surface, and a third sliding surface that are slidable on the first blade member, the second blade member, and the third blade member, respectively, and has a tapered shape such that the second sliding surface and the third sliding surface are inclined toward the first sliding surface as they proceed in the hole forming direction; When the hole is viewed from the opposite side of the hole-forming direction, a direction inclined to one side of the first direction with respect to a virtual line that passes through the center axis of the wedge member and is perpendicular to the free surface is defined as a second direction, and a direction inclined to the other side of the first direction is defined as a third direction, A rock splitting tool characterized in that, as the wedge member moves in the hole formation direction along the hole, the second blade member moves in the second direction while sliding against the second sliding surface of the wedge member, pressing against the inner wall of the hole, and the third blade member moves in the third direction while sliding against the third sliding surface of the wedge member, pressing against the inner wall of the hole.

2. The rock splitting tool according to claim 1, The fourth tip portion is a rock splitting tool finished so that the first sliding surface inclines toward the free surface as it progresses in the hole-forming direction.

3. The rock splitting tool according to claim 1, The fourth tip portion is a rock splitting tool, wherein the first sliding surface is finished to be a plane parallel to the hole-forming direction.

4. The rock splitting tool according to claim 2 or 3, The rock splitting tool, wherein the first sliding surface, the second sliding surface, and the third sliding surface are connected to each other, and the fourth tip portion is finished in a triangular pyramid shape or a triangular pyramid truncated shape.

5. A crushing method for crushing a crushable area from a drilled hole formed in advance in the direction of drilling the object to the free surface in the vicinity of the free surface of the object, A step of preparing a rock splitting tool according to any one of claims 1 to 3; a step of inserting the first tip portion of the first blade member, the second tip portion of the second blade member, the third tip portion of the third blade member, and the fourth tip portion of the wedge member into the first internal space, the second internal space, the third internal space, and the fourth internal space of the drilled hole, respectively; a step of pressing the wedge member in the hole-forming direction while applying an external force to the rear end of the wedge member while keeping the first sliding surface, the second sliding surface, and the third sliding surface in sliding contact with the first tip portion of the first blade member, the second tip portion of the second blade member, and the third tip portion of the third blade member, respectively, thereby pressing the second tip portion of the second blade member and the third tip portion of the third blade member against the inner wall of the hole, thereby splitting the rock; A crushing method comprising:

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