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JP-7856263-B2 - Pile body for the outer excavation and foundation reinforcement method and outer excavation and foundation reinforcement method

JP7856263B2JP 7856263 B2JP7856263 B2JP 7856263B2JP-7856263-B2

Inventors

  • 千種 信之
  • 長谷川 拓磨
  • 西村 裕
  • 松江 繁尚

Assignees

  • 日本コンクリート工業株式会社
  • 株式会社トーヨーアサノ

Dates

Publication Date
20260511
Application Date
20230605

Claims (5)

  1. A pile body for an external excavation and foundation reinforcement method, which is installed in a straight-shaped pile hole, A cylindrical concrete pile body, The pile body comprises a plurality of grooves, each having a groove bottom smaller in diameter than the outer diameter of the pile body, provided on the outer circumferential surface of the portion embedded in the supporting layer of the pile body, These grooves have tapered sections at the corners, and all of them, corresponding to the pile diameter, are located within a length equal to the pile diameter from the tip of the pile body, which is embedded in the supporting layer. The long-term allowable shear stress of the concrete of the pile body is 1.65 N/mm² or higher, and the short-term allowable shear stress is 2.48 N/mm² or higher. A pile body for external excavation and foundation reinforcement construction, characterized by the above features.
  2. The pile body for the external excavation and foundation reinforcement method according to claim 1, characterized in that all grooves are provided with the same shape and dimensions, and the number of grooves is set according to the pile diameter.
  3. The pile body for the external excavation and foundation reinforcement method according to claim 1, characterized in that the outer surface area of the pile body between grooves is larger than the outer surface area of the grooves, and the ratio of their areas is 1.53 to 4.11 .
  4. The process of forming a straight-shaped pile hole, The process involves injecting a root-stabilizing liquid into the support layer portion of the pile hole, The process involves further injecting pile-peripheral fixing fluid into the pile hole, A step of sinking the pile body according to any one of claims 1 to 3 into a pile hole, The process involves solidifying the root reinforcement liquid and the pile perimeter fixing liquid to form a root reinforcement section and a pile perimeter fixing section on the outer circumference of the pile body, An external excavation and foundation reinforcement method characterized by having the following features.
  5. The external excavation and foundation reinforcement method according to claim 4, characterized in that the outer diameter of the foundation reinforcement section is 1.33 times or more and 1.35 times or less the pile diameter, and the height of the foundation reinforcement section below the tip of the pile body is 1.2 times the pile diameter.

Description

This invention relates to a pile body for the external excavation and foundation reinforcement method, and to the external excavation and foundation reinforcement method. Conventionally, the external excavation and foundation reinforcement method involves excavating a straight pile hole of the same diameter along its entire length in the ground, sequentially injecting foundation reinforcement liquid and pile-perimeter fixing liquid into the pile hole, sinking a prefabricated pile, and solidifying the foundation reinforcement liquid and pile-perimeter fixing liquid to form a foundation reinforcement section and a pile-perimeter fixing section around the outer circumference of the pile (see, for example, Patent Document 1). Japanese Patent Publication No. 2019-183510 This is a cross-sectional view of a pile body used for an external excavation and foundation reinforcement method according to one embodiment of the present invention, during pile construction.This is an enlarged side view of a portion of one example of the pile structure shown above.This is an enlarged side view of a portion of another example of the same pile structure.This is a side view showing the relationship between the outer circumferential area As1 of the groove portion in the pile body and the outer circumferential area As2 of the pile body sandwiched between the groove portions.This is a cross-sectional view showing the relationship between the outer circumferential area As1 of the groove portion in the pile body and the outer circumferential area As2 of the pile body sandwiched between the groove portions.The above is a half-section view showing an example of a pile body, with (a) showing an example with a pile diameter of φ300 mm, (b) showing an example with a pile diameter of φ350 mm, (c) showing an example with a pile diameter of φ400 mm, and (d) showing an example with a pile diameter of φ450 mm.The above is a half-section view showing an example of a pile body, with (a) showing an example with a pile diameter of φ500 mm, (b) showing an example with a pile diameter of φ600 mm, and (c) showing an example with a pile diameter of φ700 mm.The above is a half-section view showing an example of a pile body, with (a) showing an example with a pile diameter of φ800 mm, (b) showing an example with a pile diameter of φ900 mm, and (c) showing an example with a pile diameter of φ1000 mm.The above is a half-section view showing an example of a pile body; (a) shows an example with a pile diameter of φ1100 mm, and (b) shows an example with a pile diameter of φ1200 mm.These are explanatory cross-sectional views showing the same external excavation and foundation reinforcement method in the order of (a) to (e).This is a cross-sectional view of test specimen A, which does not have a groove.This is a cross-sectional view of test specimen B, which has two grooves with a groove depth of 3 mm.This is a cross-sectional view of test specimen C, which has two grooves with a groove depth of 7 mm.This is an explanatory diagram showing the procedure for performing load testing on a test specimen.This is a characteristic diagram of the test results showing the relationship between the adhesion strength and pile head displacement of test specimen A-1.This is a characteristic diagram of the test results showing the relationship between the adhesion strength and pile head displacement of test specimen A-2.This is a characteristic diagram of the test results showing the relationship between the adhesion strength and pile head displacement of test specimen B-1.This is a characteristic diagram of the test results showing the relationship between the adhesion strength and pile head displacement of test specimen B-2.This is a characteristic diagram of the test results showing the relationship between the adhesion strength and pile head displacement of test specimen C-1.This is a characteristic diagram of the test results showing the relationship between the adhesion strength and pile head displacement of test specimen C-2. Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figure 1 shows a pile body labeled 1. The cross-section of the pile body 1 is shown as constructed using the external excavation and enlarged foundation reinforcement method. The pile body 1 is a precast concrete pile, constructed by forming multiple grooves (recessed grooves) 3, each having a smaller diameter than the outer diameter of the pile body 2, on the outer circumferential surface of the support layer embedded portion at the tip of the reinforced cylindrical concrete pile body 2. A steel pipe fitting 4 is attached to the tip of the pile body 2 to temporarily reduce frictional force on the outer surface of the pile and facilitate pile insertion. This pile body 1 is installed in a straight-shaped pile hole 5 along its entire length, and the foundation pile structure is formed by the foundation reinforcement portion (foundation reinforcement