JP2015183439A - Steel pipe sheet pile and installation auxiliary implement of steel pipe sheet pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel pipe sheet pile which can reduce penetration resistance generated at a joint in the installation of the steel pipe sheet pile.SOLUTION: A steel pipe sheet pile 1 comprises a main pipe 2, joint parts 3, 4 which are fastened to an external peripheral face of the main pipe, and penetration resistance alleviation means 5, 6 which disentangle and soften the ground becoming the resistance of penetration. The joint parts 3, 4 are different from each other in height positions at lower ends. The penetration resistance alleviation means 5, 6 comprise cutting parts 52, 62 including tapered shaped portions which can disentangle and cut sand and soil. Since the penetration resistance alleviation means 5, 6 alleviate the fastening of sand and soil and the pressure-tightness of the sand and soil in the inside and on an external peripheral part of an installed steel pipe sheet pile, and eliminate a penetration failure resulting from pebbles and cobblestones of the ground and a weathered bedrock becoming the penetration resistance, prior to the lower end of the joint part, the penetration resistance of the joint part can be reduced. Furthermore, even if the sand and soil is clogged in the joint of the steel pipe sheet pile which is installed last time, and the pressure-tightness occurs in the joint, since the penetration resistance alleviation means located at the lower end of a joint which is installed this time preferentially disentangles the pressure-fastened and fixed sand and soil in the joint, penetration inability can be avoided.

Description

  TECHNICAL FIELD The present invention relates to a steel pipe sheet pile and a driving aid for the steel pipe sheet pile, and in particular, a steel pipe sheet pile suitable for unraveling the penetration obstacle standing in front of a joint portion, which can be a cause of the penetration trouble of the steel pipe sheet pile, and the placement aid for the same. It is about.

  The steel pipe sheet pile generally used conventionally has a main pipe and a pair of joints integrally provided along the longitudinal direction of both sides. Each joint functions as a means for connecting steel pipe sheet piles placed in adjacent positions, and at present, joints of types such as PP joints, PT joints, and LT joints are standardized. Steel pipe sheet piles equipped with this type of joint are widely used.

  A steel pipe sheet pile including such a joint and a main pipe has a characteristic of having a high horizontal proof stress against soft ground such as sandy soil and silt. Taking advantage of such characteristics, a wall-like structure in which not only a harbor portion but also a river or a plurality of steel pipe sheet piles are interconnected via joints on the side portions is widely adopted in temporary construction such as a temporary deadline.

  In recent years, in addition to the lessons learned from the damage caused by large-scale earthquakes, the performance of steel pipe sheet piles has been highly evaluated as described above. In recent years, it has been widely used for temporary closing of deep water in the dam lake in the dam function addition work. Therefore, this steel pipe sheet pile has been applied not only to the conventional soft layer, but also to various hard ground such as gravelly soil layer, river bed sediment layer containing cobblestone, and bedrock layer.

  For such steel pipe sheet piles, a hammering method using a hydraulic hammer and a vibration method using a vibratory hammer have been performed for a long time mainly in harbors and downstream rivers. In recent years, static press-fitting devices such as a steel pipe sheet pile hydraulic press-drawing machine (steel pipe pillar) have been put into practical use, and are widely used in steel pipe sheet pile placing work.

  Since a steel pipe sheet pile enables interconnection with an adjacent steel pipe sheet pile due to the presence of the joint, the joint is an indispensable component for the steel pipe sheet pile. On the other hand, however, the existence of the “joint” projecting to the side of the steel pipe sheet pile has become an obstacle, which has been one of the factors hindering the penetration of the steel pipe sheet pile. Therefore, an improvement measure that can alleviate the penetration resistance generated in the joint portion of the steel pipe sheet pile has been strongly demanded by contractors and the like.

  In particular, due to the structural reasons of the steel pipe sheet pile, the following problems have arisen in placing the steel pipe sheet pile.

That is, for example, when a steel pipe sheet pile having a PP joint is penetrated into the ground by the above-described method, as shown in FIG. 7, earth and sand etc. enter the substantially tubular (substantially C-shaped cross section) joint, As the penetration of the steel sheet piles progresses, consolidation of the earth and sand that has entered the inside of the joint proceeds, and the density increases.
Such consolidation of earth and sand inside the joint contributes to an increase in penetration resistance and greatly impedes penetration of the steel pipe sheet pile in the middle of driving as shown in FIG.
In addition, even if the steel pipe sheet pile can be penetrated to the target depth safely against such penetration resistance, the soil and sand consolidated in the joint in the process will be the joint of the steel pipe sheet pile to be placed next time (this time This was a hindrance to the steel pipe sheet pile joint (in the inner space of the joint) and greatly hindered its penetration.
Furthermore, if the steel pipe sheet pile is forcibly driven into an adjacent position without taking any measures in the state where consolidation has occurred in the joint of the steel pipe sheet pile previously placed, the pressure in the joint of the existing steel pipe sheet pile placed previously will be The density further increases, preventing the straightness of the steel pipe sheet pile to be driven this time. As a result, the vertical accuracy is lowered, and in some cases, a fatal problem arises in that it becomes impossible to penetrate due to resistance in the ground. There was also.

Furthermore, in recent years, for example, when steel pipe sheet piles are used as water blocking walls for dam function addition work, the resistance of the joint is large due to its long length, and the main pipe is thick and has a large diameter. Because there is a large cross section, the resistance is high, and because it is placed on hard ground (rock), the penetration resistance of the ground is large, so it is used under extremely difficult construction conditions with multiple obstacles. ing.
In such a high difficulty site, before excavation of steel pipe sheet piles, replacement excavation (replaces the target ground from rock to earth) will be performed, but the consolidation of the replacement sand, Due to conditions such as large amounts of rock fragments during replacement excavation, there are many serious problems such as impossible to press-in and extremely difficult to recover and greatly delaying the process.

  Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to reduce the penetration resistance generated in the joint at the time of placing the steel pipe sheet pile. It is an object of the present invention to provide a new steel pipe sheet pile and its placing aid that can alleviate consolidation.

  The above object is a steel pipe sheet pile having a main pipe and a joint portion fixed to the outer peripheral surface thereof, and a penetration resistance relaxation means for loosening and loosening the penetration obstacle standing in front of the joint portion at the time of placing, This is achieved by a steel pipe sheet pile at the lower end of the joint portion. In addition, as a specific example of the “penetration obstacle”, for example, a ground that becomes a resistance to penetration, earth and sand that is consolidated inside the joint portion, or the like can be given.

  In the steel pipe sheet pile, it is preferable that the penetration resistance alleviating means includes a cutting portion including a tapered portion that can unravel, crush, or cut a penetration obstacle that stands in front of the joint portion at the time of placing.

  Moreover, in the said steel pipe sheet pile, the height position of the lower end of the 1st joint part which comprises the 1st joint part and 2nd joint part from which the height position of a lower end differs, and engages with the joint part of the cast steel pipe sheet pile, It is preferable that the joint portions are respectively provided so as to be higher than the height position of the lower end of the other second joint portion.

Moreover, the said objective is the coupling of the steel pipe sheet pile which comprises the 1st coupling part engaged with the coupling part of the cast steel pipe sheet pile, and the 2nd coupling part engaged with the coupling part of the steel pipe sheet pile to be cast next time. A placement assisting instrument used by attaching to a part,
A first cutting blade that is located closer to the inside of the first joint portion in bottom view and is provided so as to protrude in the penetration direction of the joint portion;
A second cutting blade that is located closer to the inside of the second joint part in bottom view and is provided so as to protrude in the penetration direction of the joint part;
This is achieved by a steel pipe sheet pile placing aid.

Moreover, the said objective is the coupling of the steel pipe sheet pile which comprises the 1st coupling part engaged with the coupling part of the cast steel pipe sheet pile, and the 2nd coupling part engaged with the coupling part of the steel pipe sheet pile to be cast next time. A placement assisting instrument used by attaching to a part,
A first reinforcing rib attached so as to be located closer to the inner side of the first joint part in a bottom view;
A second reinforcing rib attached so as to be positioned closer to the inside of the second joint part in a bottom view;
This is achieved by a steel pipe sheet pile placing aid.

In the present invention, the lower end of the joint portion is provided with an intrusion resistance relaxing means for unraveling (loosing) an intrusion obstacle made of the ground that is the resistance to intrusion or earth and sand consolidated inside the joint portion.
This penetration resistance mitigation means unravels the consolidation of soil and sand in the existing steel pipe sheet pile joint and the outer periphery of the sandstone prior to the lower end of the joint, or unravels gravel and weathered rock layers that become penetration resistance. Penetration resistance acting on the joint can be reduced. Therefore, according to the present invention, it is possible to penetrate the steel pipe sheet pile to the target depth without incurring impenetrability.
In addition, even if earth and sand are clogged in the joint of the steel pipe sheet pile previously placed and consolidation of earth and sand etc. occurs in the inner space of the joint, the penetration resistance mitigation means at the lower end of the joint to be placed this time is preceded. Since the consolidation in the joint and the caking property of the earth and sand are unraveled, it becomes possible to drive in without causing intrusion.
Therefore, according to the present invention, when a steel pipe sheet pile is driven, the natural state (before construction) of the “ground mountain” around the joint lower end before the joint lower end, cobblestone included in the ground mountain, etc. The joint of steel pipe sheet piles is used to relieve the consolidation of the joint inside and outside ground, which is caused by blocking of the penetration path due to hard obstacles and the existing steel pipe sheet pile being driven into the ground while occupying a predetermined volume. The penetration resistance acting on the part can be greatly reduced. In addition, since the consolidation of the steel pipe sheet pile previously placed is unraveled prior to the lower end of the joint, excessive penetration resistance does not act on only one joint, and as a result, when the steel pipe sheet pile penetrates. The straightness is maintained and vertical accuracy can be ensured.

Further, in the present invention, the penetration resistance mitigating means is provided with a cutting portion including a tapered portion capable of crushing compacted earth and sand or crushing hard obstacles such as cobblestones and rocks in the ground. . It is sufficient that at least one tapered portion is formed, but it is preferable that a plurality of tapered portions are formed. Specific examples of such a tapered shape portion include a shape portion protruding in a jagged shape or an external saw blade shape.
In this way, by providing the lower end of the joint with a shape portion suitable for breaking down the earth and sand, the cutting force at the lower end of the joint is increased, and the compacted state (solidified state) of the earth and sand is easily broken or collapsed. Therefore, the penetration resistance acting on the lower end of the joint portion, in particular, the penetration resistance of the joint inserted into the joint inner space of the existing steel pipe sheet pile can be reliably reduced.

In the present invention,
The height position of the lower end of the first joint part that engages with the joint part of the cast steel pipe sheet pile,
To be higher than the height position of the lower end of the second joint part on the other side,
Each of the joint portions is provided.
In this way, by providing a difference in the height position of the joint portion lower end, the lower end positions of the two joint portions to be engaged do not intersect with each other. It becomes possible to equip the members.
That is, since the heights of the two lower joint portions to be engaged are different, even if a cutting blade or a reinforcing rib is provided inside the lower end of each joint portion, these cutting blades or reinforcing ribs are not able to penetrate the joint portion. The engagement relationship is not hindered.

  Moreover, in this invention, the cutting assistance tool located in the joint part inner side is provided in the placement assistance tool attached to each joint part by bottom view. The cutting blade is attached so as to protrude in the penetration direction. By attaching such a cutting blade, when the steel pipe sheet pile is driven, the compaction of the earth and sand in the penetration direction of the joint part can be more effectively preceded, and in particular, the existing steel pipe sheet pile It becomes possible to effectively collapse the caking property of the earth and sand consolidated in the joint. As a result, it is possible to achieve the effects of further reducing penetration resistance and maintaining straightness.

  Moreover, in this invention, the reinforcement rib is attached to the placement auxiliary tool attached to each joint part so that it may be located in the joint part inner side by bottom view. By attaching such a reinforcing rib, it is possible to effectively prevent the placement assisting device at the lower end of the joint portion from buckling or deforming due to the resistance of the compacted earth and sand or the hard ground when the steel pipe sheet pile is driven.

It is the side view (partial sectional view) and bottom view showing the steel pipe sheet pile of the present invention. It is a side view (partial sectional view) which shows a mode that the steel pipe sheet pile of the present invention is driven into the object ground. It is the side view and bottom view which show the placement auxiliary tool (penetration resistance relaxation means) fixed to each joint part lower end of the steel pipe sheet pile of this invention. It is a top view which shows the positional relationship of the joint part of the existing steel pipe sheet pile, and the joint part of the steel pipe sheet pile cast this time at the time of placing the steel pipe sheet pile of this invention. It is a figure which shows the mode at the time of placing multiple steel pipe sheet piles of this invention. It is a figure which illustrates the variation of the joint shape of the steel pipe sheet pile which can apply this invention. It is a figure which shows a mode that penetration | invasion of the steel pipe sheet pile in the middle of implantation is prevented.

(Outline of features of the present invention)
As described above, the penetration resistance that acts on the joint when placing the steel pipe sheet pile is an obstacle when placing the steel pipe sheet pile. In particular, the consolidation of the earth and sand generated in the joint of the steel pipe sheet pile is a cause of the hindrance to the steel pipe sheet pile and the steel pipe sheet pile of the next placement. In other words, the ground in front of the joint at the time of casting or earth and sand clogged at the inside of the joint is stood as an “penetration obstacle (obstacle)” in the front of the joint in the direction of penetration of the steel pipe sheet pile, This greatly hinders the placement of steel sheet piles. Accordingly, one of the problems to be solved by the present invention includes the consolidation of the earth and sand generated in such a steel pipe sheet pile joint and the release of the ground in front of the joint part at the time of placing (unraveling). It is.

  In view of such a problem, in the present invention, in order to improve the cutting force particularly inside the joint part (joint inner space part), the placement aids 5 and 6 ( Intrusion resistance mitigation means) is provided.

  The placement assisting devices 5 and 6 are provided with cutting portions 52 and 62 each having a jagged shape (or a saw blade shape in a side view) extended in the penetration direction. The cutting parts 52 and 62 mainly play a role of reducing the penetration resistance by crushing the earth and sand consolidated in the joint part or the ground in front of the joint part.

  Further, the cutting assisting tools 5 and 6 (penetration resistance mitigating means) are fixedly provided with cutting blades 53 and 63 protruding from the lower ends thereof. The cutting blades 53 and 63 also serve as reinforcing members for preventing buckling and deformation of the placement assisting instrument (penetration resistance mitigating means).

  The placement assisting instrument having such a cutting part and a cutting blade is attached to at least one joint part lower end of the steel pipe sheet pile. Here, “one side” refers to the joint portion on the side inserted into the joint inner space of the cast steel sheet pile. Of course, you may attach to each of the joint part of the both sides of a steel pipe sheet pile.

  And, by attaching such a driving aid to at least the lower end of one joint portion of the steel pipe sheet pile, the cutting blade and the cutting portion of the casting auxiliary tool precede the joint when placing the steel pipe sheet pile. It reaches the inside, and the pressure input and impact force (propagating from a press-fitting machine, etc.) are concentrated and transmitted to the consolidated soil in the joint inner space.

  Therefore, according to the steel pipe sheet pile provided with the above-mentioned placing assist device (penetration resistance mitigation means), the “penetration obstacle” such as the consolidation of earth and sand generated in the joint inner space of the existing steel pipe sheet pile and the ground that obstructs the progress of the joint portion. Even in the case where there is, it is possible to loosen, break down, or cut off these penetration obstacles, and it is possible to place a steel pipe sheet pile as designed.

  Hereinafter, specific embodiments of the steel pipe sheet pile and the driving aid of the present invention will be described.

(Structure of steel pipe sheet pile)
Based on FIG.1 and FIG.2, the structure of the steel pipe sheet pile of this invention is demonstrated.
FIG. 1 is a side view (partial sectional view) and a bottom view showing a steel pipe sheet pile as a representative example of the present invention.
FIG. 2 is a side view (partial cross-sectional view) showing a state in which the steel pipe sheet pile of FIG. 1 is driven into the target ground.

The steel pipe sheet pile 1 of this embodiment is as shown in FIG.
A main pipe 2 (casing) forming the main body of the steel pipe sheet pile 1;
A pair of joint parts 3, 4 of the type called PP joints;
・ Placement aids 5 and 6 (penetration resistance mitigation means) fixed to the lower end of each joint part;
A casing top 7 (main pipe lower end protection member) fixed to the lower end side of the main pipe 2;
have.

  The main pipe 2 (casing) is configured similarly to the main pipe of a conventional steel pipe sheet pile, and a substantially annular casing top 7 is provided at the lower end of the main pipe 2. The specific role of the casing top 7 forming the main pipe lower end protecting member will be described later.

  The joint portions 3 and 4 having a substantially C-shaped cross section are joints of a type generally referred to as a PP joint, and are formed by a substantially tubular member having a slit formed along the longitudinal direction. Yes. Each joint portion is fixed to the outer peripheral surface along the longitudinal direction of the main pipe 2. The joint portions 3 and 4 play a role of connecting the steel pipe sheet piles in cooperation with the joint portion of the steel pipe sheet pile placed in the adjacent position.

  As shown in FIG. 2, the short first joint portion 3 located on the left side of the drawing engages with a joint portion 4 'of an existing steel pipe sheet pile 1' placed at an adjacent position. When the steel pipe sheet pile 1 is penetrated into the target ground, the first joint part 3 is partially inserted into the inner space of the joint part 4 ′ of the existing steel pipe sheet pile 1 ′ placed in advance ( 5), the main pipe 2 is integrated with the target ground. In the process of penetration, the first joint part 3 is slidably engaged with the joint part 4 'of the existing steel pipe sheet pile 1'.

  The long second joint portion 4 located on the right side of the drawing is engaged with the joint portion when a steel pipe sheet pile (steel pipe sheet pile for the next placement) is placed at an adjacent position. As shown in FIG. 4, the second joint portion 4 does not engage with other joint portions when the steel pipe sheet pile penetrates into the target ground. When a steel pipe sheet pile is placed, it engages with the joint.

  As shown in FIG. 1, the joint portions 3 and 4 having different lengths are attached to the main pipe 2 so that the height positions of the lower ends thereof are different. That is, as shown in FIG. 2, the height position of the lower end of the first joint part 3 engaged with the joint part 4 ′ of the cast steel pipe sheet pile 1 ′ is the height of the lower end of the second joint part 4 on the other side. These joint portions are provided so as to be above the position.

  The placement aids 5 and 6 that function as penetration resistance mitigating means are fixed to the lower ends of the joint portions 3 and 4, which are “consolidated and consolidated soil and sand in front of the lower ends of the joint portions, It plays the role of unraveling the causes of resistance caused by hard obstacles such as cobblestones and rocks. Details of the placement assisting devices 5 and 6 will be described later.

  The casing top 7 fixed on the lower end side of the main pipe 2 has a small diameter portion 71 inscribed on the lower end inner wall side of the main pipe 2 and a large diameter portion 73 protruding from the lower end of the main pipe 2. The large-diameter portion 73 is formed thick so as to cover the lower end of the main pipe from hard obstacles and excavation bits below it, and plays a role of protecting the lower end of the main pipe from buckling and deformation. .

  When the steel pipe sheet pile 1 having the above-described configuration is placed on the target ground, for example, as shown in FIG. 2, a drilling device 90 including a drill bit 91 (expansion bit) that can be expanded and contracted is inserted into the main pipe 2. And set it on the target ground. The hole drilling device 90 illustrated in FIG. 2 includes a drill rod 91 that can be expanded and contracted, a drill rod connected to a rotary drive device, a down-the-hole hammer, and the like.

As shown in FIG. 2, when the excavation bit 91 is protruded from the lower end of the main pipe 2 and the drilling bit 91 is set in an expanded state to start drilling, the steel pipe sheet pile 1 is built in the hole simultaneously with the progress of drilling. Is included.
In this process, the main pipe 2 sinks due to its own weight in a state where the peripheral surface friction is very small, and always stands in a state where it is in contact with the upper surface of the excavation bit 91 in the drilling hole. Therefore, if the bottom of the main pipe 2 is not protected at all, there is a risk of buckling or deformation at the lower end of the main pipe due to its own weight. In the present invention, the casing top 7 is welded to the lower end of the main pipe 2 for reinforcement. This protects the lower end of the main pipe (the bottom of the main pipe).
On the other hand, when circumferential friction increases, it becomes difficult for the steel pipe sheet pile 1 to sink due to its own weight. FIG. 2 shows this state. Therefore, in the present invention, the inner peripheral diameter of the casing top 7 wrapped on the inner wall of the main pipe 2 is made smaller than the outer diameter of the device upper end (ring-shaped step portion 93) of the hole drilling device 90. As a result, the upper end of the device (ring-shaped stepped portion 93 of the hole drilling device) and the upper end of the casing top 7 interfere with each other in the vertical direction, so that the weight of the hole drilling device 90 reaches the main pipe 2 through these contact portions. As a result, the subsidence of the steel pipe sheet pile 1 follows the drilling promotion.

(Configuration of the placement aid)
Next, a specific configuration of the placement assisting devices 5 and 6 functioning as penetration resistance reducing means will be described with reference to FIG. FIG. 3 is a side view and a bottom view showing the placement assisting devices 5 and 6 (penetration resistance relaxation means) fixed to the lower ends of the joint portions of the steel pipe sheet pile 1.

The first placement assisting instrument 5 is fixed to the lower end of the first joint part 3 on the left side of the drawing.
As shown in FIGS. 3 (a1) and (a2), the first placement assisting instrument 5 is
A main body 51 having a substantially C-shaped cross section, similar to the joint portion 3;
A saw-shaped cutting portion 52 that can cut through the earth and sand (ie, saw-toothed in a side view);
A cutting blade 53 (reinforcing rib) having a substantially T-shape when viewed from the bottom;
It is comprised including.

  As shown in FIGS. 3 (a1) and (a2), the substantially annular main body 51 in which slits are formed in the same manner as the first joint portion 3 is aligned with the slits 31 and 54 so that they are linearly connected. It is welded to the tip of one joint part 3.

  On the lower end side of the main body 51 of the first placement assisting tool 5, a cutting portion 52 including a plurality of tapered portions capable of cutting the earth and sand is formed. The cutting part 52 illustrated in the present embodiment is formed in a jagged shape (that is, a sawtooth shape in a side view) as a representative example. Note that the shape of the cutting part 52 is not necessarily limited to that shown in the drawings, and any other shape (not shown) may be used as long as it is a shape capable of cutting down compacted sediment or consolidated sediment in advance. Even if it exists, it can be adopted. That is, in this embodiment, the sawtooth-shaped tapered portion constituting the cutting portion protrudes with a uniform length as an example, but various other modes can be formed. For example, you may form so that only the taper-shaped part in a fixed range protrudes below (namely, placement direction) rather than another part. Specifically, in each cutting part, it is possible to change the length of the tapered part (the jagged part) or make a step between the main part and the opposite side. That is, it is possible to make the extension length of the tapered portion of each cutting portion uneven. It is also possible to change the inclination angle of the tapered portion in accordance with the part.

  As shown in FIG. 3 (a2), a cutting blade 53 having a substantially T-shape in bottom view protrudes from the lower end of the main body 51 in the penetration direction on the inner side of the main body 51 of the first placement assisting tool 5. Has been. The cutting blade 53 also serves as a reinforcing rib for reinforcing the main body 51 of the first placement assisting device.

  When the steel pipe sheet pile 1 is driven, the first joint portion 3 is inserted into the inner space of the existing side joint portion 4 ′ in the positional relationship shown in the lower side of FIG. The substantially T-shaped cutting blade 53 on the lower end side of 3 does not disturb the mutual insertion state of the joint portions 3 and 4 ′. That is, the cutting blade 53 on the first joint part 3 side is formed in a substantially T shape when viewed from the bottom, and a clearance through which the insertion part of the joint part 4 ′ can be inserted is secured. The cutting blade 53 on the first joint portion 3 side does not become an obstacle.

  The second placement assisting device 6 is fixed to the lower end of the second joint portion 4. As shown in FIGS. 3 (b1) and 3 (b2), the second placement assisting device 6 has a substantially tubular main body 61 without slits and a jagged shape (that is, a sawtooth shape in a side view) capable of breaking the earth and sand. ) And a cutting blade 63 (reinforcing rib) that is substantially cross-shaped when viewed from the bottom.

  The substantially tubular main body 61 is welded to the tip of the second joint portion 4. The main body 61 is not formed with a slit, and is different from the main body 51 on the first placement assisting instrument side in this respect.

  On the lower end side of the main body 61 of the second placement assisting tool, a cutting portion 62 including a plurality of tapered portions capable of cutting the earth and sand is formed. The cutting part illustrated in this embodiment is formed in a jagged shape (that is, a sawtooth shape in a side view) as a representative example. The shape of the cutting part is not necessarily limited to that shown in the figure, and any other shape not shown may be adopted as long as it can cut the compacted earth and sand in advance. it can.

  As shown in FIG. 3 (b2), a cutting blade 63 having a substantially cross shape when viewed from the bottom is welded to the inside of the main body 61 of the second placement assisting instrument in a state of protruding from the lower end of the main body 61 in the penetration direction. Yes. The cutting blade 63 also serves as a reinforcing rib 63 for reinforcing the main body 61 of the second placement assisting tool.

(Functions and actions when placing steel pipe sheet piles)
The steel pipe sheet pile 1 having the above-described configuration is continuously driven so as to form a wall body formed by connecting a plurality of steel pipe sheet piles, for example, as illustrated in FIG.

  At the time of placing each steel pipe sheet pile, first, as shown in FIG. 5, the short length of the steel pipe sheet pile 1 to be placed this time is inserted into the long joint portion 4 ′ (second joint portion) of the existing steel pipe sheet pile 1 ′. The joint part 3 (first joint part) is positioned.

  Subsequently, in a state where a part of the short joint portion 3 (first joint portion) is inserted into the inner space of the long joint portion 4 ′ (second joint portion) of the existing steel pipe sheet pile 1 ′, The steel pipe sheet pile 1 is penetrated into the ground. For the penetration of the steel pipe sheet pile 1, for example, a drilling device 90 illustrated in FIG. 2 is used. The penetration principle using the drilling device is as described above.

  Then, as shown in FIG. 2, when the drilling device 90 is passed through the main pipe 2 of the steel pipe sheet pile and the excavation bit 91 at the tip thereof is set in the diameter-expanded state, the drilling is started according to the principle described above. The steel pipe sheet pile 1 is built in the hole simultaneously with the progress of the hole.

  In this drilling process, since the excavation bit 91 performs excavation with a diameter larger than the outer diameter of the main pipe, the main pipe 2 drawn into the hole as shown in FIG. However, in the penetration direction of the joint portions 3 and 4, uncut hole soil and sand (sand that could not be excavated by the preceding excavation bit 91) is still left behind.

  However, in the present invention, as shown in FIG. 2, the placement assisting devices 5 and 6 are fixed to the tips of the joint portions 3 and 4. That is, the striking force from the down-the-hole hammer of the hole drilling device 90 and the pressure input accompanying the striking are propagated to the placing aids 5 and 6 via the main pipe 2 and the joint portions 3 and 4, and further this propagated striking The force and pressure input are propagated to the consolidated soil in the joint traveling direction. Therefore, the cutting portions 52 and 62 of the placement aids 5 and 6 and the cutting blade 53, the ground that is fatigued due to the previous drilling by the excavation bit 91, or the ground in which gravel or rock crush is present, are arranged. It is possible to cut ahead by 63.

  A part of the earth and sand shaved by the placement aids 5 and 6 collapses through the gap 8 generated by the preceding excavation by the excavation bit 91 and is taken into the inside from the front end side of the main pipe, and the ground is blown by air blow. It will be dumped to the front side.

  Moreover, about the 1st joint part 3 inserted partially inside the joint part 4 'of the existing steel pipe sheet pile 1', the cutting part 52 and the cutting blade 53 in the front-end | tip part are the impact vibration which propagates from a down the hole hammer. Ripple and pressure input. Then, the sand and sand compacted in the joint portion 4 ′ of the existing steel pipe sheet pile 1 ′ is unraveled as if it is repeatedly chopped, and the caking property is collapsed. Therefore, since the pressure density in the joint part 4 ′ of the existing steel pipe sheet pile 1 ′ can be reduced by the driving aid 5 provided at the tip of the joint part 3, according to the present invention, the steel pipe sheet pile joint part Excellent effects such as penetration are achieved.

Thus, according to the present invention described above, the penetration resistance acting on the joint portion can be relaxed by unraveling the compaction of the earth and sand by the placement assisting tool preceding the lower end of the joint portion. It is possible to penetrate the sheet pile.
In addition, even if earth and sand are clogged in the joint of the steel pipe sheet pile previously placed and consolidation occurs in the inner space of the joint, the placement assisting tool at the lower end of the joint to be placed this time is preceded by the consolidation in the joint. Since it unraveles (solidification property of earth and sand), it becomes possible to drive in reliably without causing impenetrability.
Therefore, according to the present invention, when the steel pipe sheet pile is driven, the compression of the “ground mountain” around the joint lower end is unraveled and the penetration resistance acting on the joint portion of the steel pipe sheet pile can be greatly reduced. . In addition, since the consolidation of the steel pipe sheet pile previously placed is unraveled prior to the lower end of the joint, excessive penetration resistance does not act on only one joint, and as a result, when the steel pipe sheet pile penetrates. The straightness is maintained and vertical accuracy can be ensured.

  Further, in the present invention, the placement assisting instrument is provided with a cutting portion including a tapered portion capable of cutting the earth and sand. In this way, by giving the joint lower end a shape suitable for breaking up earth and sand, the cutting force at the lower end of the joint is increased and the compacted state (solidified state) of the earth and sand can be easily collapsed. Thus, the penetration resistance acting on the lower end of the joint portion, particularly the penetration resistance of the joint inserted into the joint inner space of the existing steel pipe sheet pile can be reliably reduced.

(Other embodiments of the present invention)
The embodiment described above is an exemplary embodiment of the present invention described in the claims, and is not intended to limit the technical scope of the present invention. In other words, the present invention described in the claims includes various embodiments such as construction by a construction machine such as a vibro hammer and a pillar (steel pipe sheet pile hydraulic press) other than the above-described embodiments. I want to be.

  Moreover, for example, in the above-described embodiment, a steel pipe sheet pile having a joint portion of a type called a PP joint shown in FIG. 6A is adopted, but as shown in FIGS. 6B and 6C. It is also possible to apply the present invention to a steel pipe sheet pile having a joint portion of a type such as a PT joint or an LT joint.

1 Steel pipe sheet pile 1 'Existing steel pipe sheet pile 2 cast (main casing)
3 1st joint part 31 Slit 4 2nd joint part 5 1st placement auxiliary instrument (penetration resistance relaxation means / consolidation relaxation means)
51 Body 52 Cutting part 53 Cutting blade (reinforcing rib)
54 Slit 6 Second placement aid (penetration resistance mitigation means / consolidation mitigation means)
61 Body 62 Cutting part 63 Cutting blade (reinforcing rib)
7 Casing top (main pipe lower end protection member)
71 Small-diameter portion 73 Large-diameter portion 8 Substantially cylindrical gap 90 Drilling device 91 Drilling bit (expansion bit)
93 Ring-shaped step

Claims (5)

  A steel pipe sheet pile having a main pipe and a joint portion fixed to the outer peripheral surface thereof, and having a penetration resistance relaxation means for loosening a penetration obstacle standing in front of the joint section at the lower end of the joint section. Steel pipe sheet pile.   The said penetration resistance mitigation means is equipped with the cutting part containing the taper-shaped part which can loosen or crush or break down the penetration obstacle which stands in front of a joint part, The Claim 1 characterized by the above-mentioned. Steel pipe sheet pile. Comprising a first joint part and a second joint part having different height positions at the lower end;
The height position of the lower end of the first joint part engaged with the joint part of the cast steel sheet pile is
To be above the height position of the lower end of the other second joint part,
The steel pipe sheet pile according to claim 1, wherein the joint portions are respectively provided. Used by attaching to a joint part of a steel pipe sheet pile comprising a first joint part engaging with a joint part of a cast steel pipe sheet pile and a second joint part engaging with a joint part of a steel pipe sheet pile to be placed next time. In the placement assisting device,
A first cutting blade that is located closer to the inside of the first joint portion in bottom view and is provided so as to protrude in the penetration direction of the joint portion;
A second cutting blade that is located closer to the inside of the second joint part in bottom view and is provided so as to protrude in the penetration direction of the joint part;
A steel pipe sheet pile placing aid. Used by attaching to a joint part of a steel pipe sheet pile comprising a first joint part engaging with a joint part of a cast steel pipe sheet pile and a second joint part engaging with a joint part of a steel pipe sheet pile to be placed next time. In the placement assisting device,
A first reinforcing rib attached so as to be located closer to the inner side of the first joint part in a bottom view;
A second reinforcing rib attached so as to be positioned closer to the inside of the second joint part in a bottom view;
A steel pipe sheet pile placing aid.