JP2005113467A - Method of constructing reinforced soil abutment and pier, and structures of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of constructing a reinforced soil abutment and a pier, which facilitates maintenance of a bridge, simplifies the structure of an anchorage portion, and contributes to cost reduction, and to provide structures of the reinforced soil abutment and the pier. <P>SOLUTION: According to the method of constructing the reinforced soil abutment and the pier, (a) a finished thickness of each layer of gravelly soil (cement stabilized soil) 2 such as size-regulated debris mixed with cement is set to 50 to 15 cm, and each layer is rolled such that a compaction degree is set to 90 % or more, (b) followed by arranging a tensile reinforcing member 3 on each finished surface. Then (c) the steps of (a) and (b) are repeatedly carried out until the layers are piled up to a predetermined height, to thereby construct a reinforced mound body. Further (d) a small abutment 6 is set on an upper portion of the piled-up reinforced mound body, for mounting thereon a bridge girder 7, and then (e) cast-in-place concrete wall works 5 are set on an open surface of the reinforced mound body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a construction method of a reinforced earth abutment / pier and a structure thereof.

  Conventionally, as a method for constructing a reinforced earth abutment by installing a small abutment on the upper end of the reinforced earth wall, the following methods are generally used.

  FIG. 5 is a schematic view showing a conventional method for constructing a reinforced earth bridge.

  In this figure, 100 is the ground, 101 is a crushed stone, 102 is a geotextile, 103 is embankment, 104 is a wall work, 105 is a small abutment, and 106 is a bridge girder.

  In this method, as shown in the following Patent Document 1, it is assumed that a reinforced soil wall composed of a grain size-adjusted crushed stone 101, geotextile 102, embankment 103, and wall work 104 can sufficiently support the load of the small abutment 105 or the bridge girder 106. Therefore, a method has been generally used in which a reinforced earth wall having a high wall rigidity and a high load bearing capacity is constructed using a high-quality embankment material such as the particle size-adjusted crushed stone 101, and a small abutment 105 is installed thereon. In fact, this method has several decades of construction experience as a railway abutment. However, since there is a limit to the load that can be supported, it was usually applied to an abutment with a girder length of 15 m or less.

  Therefore, as a method capable of supporting a larger load such as a long girder, the following method is used.

  FIG. 6 is a schematic diagram showing a conventional PL / PS (preloaded prestress) reinforced earth method.

As shown in Patent Document 2 below, this construction method applies a load history (preload) in advance to a reinforced embankment composed of a grain size-adjusted crushed stone 101, geotextile 102, and embankment 103 by means of a vertical tension material 111, and the load is about half. By unloading and fixing the vertical tension member 111 in a prestressed state, the load bearing capacity and compression rigidity of the reinforced embankment are significantly improved compared to the method of FIG. In particular, when the reinforced embankment is made by compacting with a reticulated material such as a particle size-adjusted crushed stone 101, a remarkable effect can be obtained, and it can be applied even with a digit of 50 m or more. This type of pier was adopted at one place in railway construction, and has a track record of fully supporting train loads as a temporary pier for 4 years.
Japanese Patent Publication No. 4-53204 Patent No. 28895401

  However, as a drawback of the above-mentioned PL / PS (preloaded prestress) reinforced earth method, the prestress due to the vertical tension material 111 is small but relaxed (stress relaxation) due to creep deformation of the reinforced embankment. When using for a long time, it is necessary to periodically retighten the vertical tension member 111 or to arrange a spring or the like that can follow the deformation in the fixing part of the vertical tension member 111 and the small abutment 105.

  For this reason, problems have been pointed out, such as an increase in maintenance labor or a complicated fixing portion, which is not economical. Therefore, there are still no cases adopted for permanent structures.

  In view of the above circumstances, an object of the present invention is to provide a method for constructing a reinforced earth abutment / pier and a structure thereof, which can be easily maintained, a fixing portion can be simplified, and costs can be reduced.

In order to achieve the above object, the present invention provides
[1] In the construction method of the reinforced earth abutment / pier, (a) the cement-stabilized soil is set to a finished thickness of 50 to 10 cm, and rolled by layer so that the compaction degree is 90% or more. b) A tensile reinforcing material is arranged on the finished surface, and (c) the steps (a) and (b) are repeated to build up a reinforced embankment by stacking up to a predetermined height. A small abutment for placing a bridge girder is installed on the upper part of the reinforced embankment formed, and (e) a cast-in-place concrete wall construction is installed on the open surface of the reinforced embankment.

  [2] A reinforced earth abutment / pier pier structure, which is constructed by the construction method of the reinforced earth abutment / pier pier described in [1] above, a reinforced embankment with cement-stabilized soil, and a small abutment for installing a bridge girder Have

  [3] In the construction method of reinforced soil abutments and piers, (a) embankment bodies are installed on the ground, vertical tension materials are placed in the vertical direction using them as reaction force, and (b) the cement-stabilized soil is finished. The thickness is set to 50 to 15 cm, and the layers are rolled for each layer so that the degree of compaction is 90% or more, (c) a tensile reinforcing material is disposed on the finished surface, and (d) (b), ( By repeating the step c), a reinforced embankment is constructed by stacking up to a predetermined height, (e) a small abutment for placing a bridge girder is installed on the upper part of the accumulated reinforced embankment, and (f) The small abutment and the vertical tension member are fastened and connected, and (g) a cast-in-place concrete wall surface is installed on the reinforced embankment open surface.

  [4] Reinforced clay abutment / pier pier structure, which is constructed by the method of constructing a reinforced earth abutment / pier according to the above [3], and is provided with a reinforced embankment, a vertical tension member, and a bridge girder with the cement-stabilized soil It has a small abutment.

  [5] In the construction method of the reinforced earth abutment / pier, in the construction method of the reinforced earth abutment / pier, the cushioning material is further arranged between the small abutment and the wall surface.

  [6] A reinforced earth abutment / pier pier structure comprising a buffer material between the small abutment and the wall surface constructed by the construction method of the reinforced earth abutment / pier pier according to claim 5.

  According to the present invention, the following effects can be achieved.

  It is possible to support long girder reasonably including during an earthquake. Moreover, since the abutment / pier according to the present invention is a structure made of soil, the cost can be reduced as compared with a conventional reinforced concrete structure.

  In addition, maintenance is easy and the fixing unit can be simplified.

  Pre-mixed cement and other solidified powders to a high-quality embankment material such as grain size-adjusted crushed stone, and then fully compacted them to construct a reinforced embankment for abutments and piers with cement-stabilized soil. . This makes it possible to extremely increase the shear strength of the reinforced embankment.

  Hereinafter, embodiments of the present invention will be described in detail.

  As described above, when the reinforced embankment is used as an abutment or a pier, a large load due to the weight of the small abutment or the bridge girder acts on the reinforced embankment for a long period of time. Since the reinforced embankment has a gap, it is basically a highly compressible material. Therefore, in order to suppress the residual settlement due to bridge girder loads and train loads, load history (preload) is applied to the reinforced embankment in advance before these loads act, as in the PL / PS reinforced earth method described above. It is effective to give. However, this construction method has problems related to the fixing portion, maintenance, and economy as described above.

  As another method of suppressing deformation that can solve these problems, a method of extremely increasing the shear strength and rigidity of the reinforced embankment itself can be considered.

  FIG. 1 is a schematic view showing a reinforced earth abutment showing a first embodiment of the present invention.

  In this figure, 1 is the ground, 2 is a repellent soil such as a grain-sized crushed stone mixed with cement (cement stable treated soil; cement stabilized treated approach block), 3 is a geotextile (tensile reinforcement), 4 is embankment, 5 is Wall work, 6 is a bridge, 7 is a bridge girder. In addition, as the tensile reinforcement member 3, a wire mesh or the like may be used in addition to the geotextile.

  In this method, solidified powder such as cement is pre-mixed with a high-quality embankment material such as conventional crushed stone, and a reinforced embankment with cement-stabilized soil 2 is constructed. To do. Conventionally, cement stabilization treatment has been performed to improve malicious embankment materials such as cohesive soil, and to simplify construction such as rolling compaction even if it is good quality soil. Although the construction method of this example uses a high-quality soil such as a grain-size-adjusted crushed stone and arranges a tensile reinforcement such as geotextile 3 and a welded wire mesh, a sufficient cement rolling treatment is performed and sufficient rolling is performed. It is characterized by performing pressure. This makes it possible to extremely increase the shear strength of the reinforced embankment.

Hereinafter, the construction method of the reinforced earth abutment / pier will be described with reference to FIG.
(1) Set the finished thickness of 50 to 10 cm of reclaimed soil (cement stabilized soil) 2 such as particle size-adjusted crushed stone mixed with cement, and roll it for each layer so that the compaction degree is 90% or more. ,
(2) Place tension reinforcement 3 such as geotextile or wire mesh on the finished surface of each layer,
(3) By repeating the steps (1) and (2) above, stacking up to a predetermined height,
(4) A small abutment 6 for placing the bridge girder 7 is installed on the upper part of the stacked reinforcing embankment,
(5) A cast-in-place concrete wall work 5 is installed on the open side of the reinforced embankment.

By such a process, it is possible to construct an abutment / pier pier structure composed of a reinforced embankment made of cement-modified crushed stone and a small abutment for installing a bridge girder. FIG. 2 is an example in which the strength of a reinforced embankment made of cement-stabilized soil according to the present invention was measured in a triaxial compression test. In this figure, the horizontal axis indicates the axial strain ε _a (%), and the vertical axis indicates the axial differential stress q (kP _a ). In this test, only 50 kg of cement was added to 1 m ^{3 of} particle size-adjusted crushed stone, and specimens with varying dry density ρ _d were prepared by adjusting the rolling energy and the strength was compared in that case. It was.

  As is clear from this figure, it can be confirmed that when the rolling density is sufficiently increased and the dry density is increased, the strength is extremely increased as compared with the case where the dry density is not increased. Moreover, although not shown in figure, compared with the soil which does not add a cement, although depending on the addition amount, the intensity | strength increase of several times-dozens of times is obtained.

  Therefore, according to the present embodiment, it is possible to support a large girder without adding a PL / PS reinforced earth method by using a reclaimed soil (cement stable treated soil) such as a particle size-adjusted crushed stone mixed with cement. A sufficient shear strength can be secured.

  FIG. 3 is a schematic view showing a reinforced earth abutment showing a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part which is common in 1st Example.

  In this figure, 11 is a vertical tension material for keeping the abutment 6 so as not to rotate or slide, and 12 is a fastening nut for the vertical tension material 11.

  In the first embodiment described above, it has sufficient strength against vertical loads such as long girders. However, particularly when an extremely large horizontal inertia force acts on the small abutment as in a large earthquake, the small abutment It is assumed that the horizontal stability of the small abutment 6 cannot be secured due to separation between the upper end of the reinforced embankment due to the sliding and rotational movement of 6.

  In such a case, as shown in FIG. 3, it is effective to fix the small abutment 6 using the vertical tension material 11. In this case, unlike the conventional PL / PS reinforced earth method shown in FIG. 6, the vertical tension member 11 does not have a role of acting or holding a predetermined load in the vertical direction, and the small abutment 6 rotates during an earthquake. Or, since it only serves to keep it from sliding, it is not particularly necessary to arrange a spring or the like in the fixing portion. Therefore, since it is only necessary to fasten and put the vertical tension member 11 with the fastening nut 12 or the like, the fixing becomes simple, and the horizontal stability of the small abutment 6 at the time of an earthquake or the like is dramatically increased.

Hereinafter, the construction method of the small abutment / pier will be described with reference to FIG.
(1) An embankment body is installed on the ground 1, and vertical tension members 11 such as PC steel bars are arranged in the vertical direction using them as a reaction force,
(2) After that, roll the clay (grain stabilized crushed stone) 2 mixed with cement to a finished thickness of 50 to 10 cm and roll it for each layer so that the compaction degree is 90% or more. Press,
(3) Place tensile reinforcement 3 such as geotextile or wire mesh on the finished surface of each layer,
(4) By repeating the steps (2) and (3) above, stacking up to a predetermined height,
(5) A small abutment 6 for placing the bridge girder 7 is installed on the upper part of the stacked reinforcing embankment,
(6) The small abutment 6 and the vertical tension member 11 are connected by tightening with the fastening nut 12.
(7) Finally, the open face of the reinforced embankment is covered with cast-in-place concrete wall work 5 or the like. As described above, according to the present embodiment, the vertical tension material is applied to the reinforced embankment composed of the embankment material made of reticulated soil (cement stable treated soil) such as particle-size-adjusted crushed stone mixed with cement and the tensile reinforcement material such as geotextile. By fixing, rotation and sliding of the abutment can be prevented, and stability not only in the vertical direction but also in the horizontal direction can be ensured.

  FIG. 4 is a schematic view showing a reinforced earth abutment according to a third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part which is common in 1st Example.

  In this figure, reference numeral 21 denotes a cushioning material disposed between the front end surface of the small abutment 6 and the wall surface work 5.

  A method of suppressing the sliding of the small abutment 6 at the time of the earthquake described in the second embodiment with the wall construction 5 of the reinforced embankment is also conceivable. However, as shown in FIG. 1 of the first embodiment, when the sliding of the small abutment 6 at the time of the earthquake is suppressed at the upper end of the wall surface work 5 through the cement stabilization soil 2, a large force is applied to the wall surface work 5. Will work. In order to withstand such a large force and suppress the sliding of the small abutment 6, the cross section of the wall of the wall surface work 5 must be enlarged, which is not economical.

  Therefore, as shown in FIG. 4, by placing a cushioning material 21 such as foamed polystyrene or foamed urethane between the small abutment 6 and the wall surface work 5, an impact load caused by an earthquake is buffered and acts on the wall work 5. By reducing the force to perform, sliding of the small abutment 6 can be suppressed by the conventional wall work 5.

  In addition, this invention is not limited to the said Example, A various deformation | transformation is possible based on the meaning of this invention, and these are not excluded from the scope of the present invention.

  The construction method and structure of the reinforced earth abutment / pier of the present invention and its structure are easy to maintain, simplify the anchoring part, and reduce costs. In particular, the construction of the abutment / pier that supports long girder is possible. Suitable for

It is a schematic diagram which shows the reinforced earth abutment which shows 1st Example of this invention. It is a figure which shows the example which measured the intensity | strength of the reinforced embankment concerning this invention by the triaxial compression test. It is a schematic diagram which shows the reinforced earth abutment which shows 2nd Example of this invention. It is a schematic diagram which shows the reinforced earth abutment which shows 3rd Example of this invention. It is a schematic diagram which shows the construction method of the conventional reinforced earth abutment. It is a schematic diagram which shows the conventional PL / PS (preloaded prestress) reinforced earth method.

Explanation of symbols

1 Ground 2 Cement stabilized soil (Leki soil such as particle size-adjusted crushed stone mixed with cement; Cement stabilized treatment approach block)
3 Geotextile (tensile reinforcement)
4 Embankment 5 Wall Work 6 Kohashidai 7 Bridge Girder 11 Vertical Tensile Material 12 Fastening Nut of Vertical Tensile Material 21 Buffer Material

Claims (6)

(A) Set the cement-stabilized soil to a finished thickness of 50 to 10 cm and roll it for each layer so that the compaction degree is 90% or more,
(B) placing a tensile reinforcement on the finished surface;
(C) By repeating the steps (a) and (b) above, a reinforced embankment is constructed by stacking up to a predetermined height,
(D) A small abutment for placing a bridge girder is installed on top of the stacked reinforcing embankment,
(E) A method for constructing a reinforced earth abutment and pier, wherein a cast-in-place concrete wall surface is installed on the open surface of the reinforced embankment.   A reinforced earth abutment / pier pier structure having a reinforced embankment with cement-stabilized soil and a small abutment for installing a bridge girder constructed by the construction method of a reinforced earth abutment / pier pier according to claim 1. (A) The embankment body is installed on the ground, and the vertical tension members are arranged in the vertical direction using them as reaction force,
(B) Thereafter, the cement-stabilized soil is set to a finished thickness of 50 to 10 cm, and rolled for each layer so that the compaction degree is 90% or more,
(C) placing a tensile reinforcement on the finished surface;
(D) By repeating the steps (b) and (c), a reinforced embankment is constructed by stacking up to a predetermined height,
(E) A small abutment for placing a bridge girder is installed on top of the stacked reinforced embankment,
(F) Tighten and connect the abutment and the vertical tension material,
(G) A method for constructing a reinforced earth abutment and pier, wherein a cast-in-place concrete wall surface is installed on the open surface of the reinforced embankment.   A reinforced earth abutment / pier structure having a small abutment for installing a reinforced embankment, a vertical tension member, and a bridge girder constructed by the cement-stabilized soil, constructed by the construction method for a reinforced earth abutment / pier pier according to claim 3.   The construction method of the reinforced earth abutment / pier according to claim 1, further comprising a buffer material disposed between the small abutment and the wall surface.   A reinforced earth abutment / pier pier structure comprising a cushioning material between the small abutment and the wall surface constructed by the construction method of the reinforced earth abutment / pier according to claim 5.

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