JP2000145354A - Deep foundation excavation method in bedrock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently excavate bedrock and shorten the term of construction work without disturbing neighboring districts when forming a deep foundation in a place where there is a bedrock portion underground. SOLUTION: In this deep foundation excavation method, a small-diameter pilot excavation hole 8 is excavated in the central part of the deep foundation pile 6 from the ground surface to a length of the deep foundation pile 6, a plurality of bore holes 9, 9 are provided by a boring machine in the bedrock between the outer diameter 6a of the deep foundation pile 6 and the outer diameter of the pre-excavated hole 8, thereafter, the inside of the bore holes 9, 9 is filled up with an expansive material 10 mixed with water or absorbing water, and the bedrock B is crushed by an expanded pressure generated by a reaction with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep foundation excavation method for forming a pile in the ground, and more particularly to a deep foundation excavation method for forming a pile in the underground rock.

[0002]

2. Description of the Related Art Conventionally, as a deep foundation excavation method in rock, a drill is drilled in a rock, an explosive is set in the drill, and blasting is performed. 2. Description of the Related Art There is known a construction method in which soil and the like are divided into small pieces by a breaker or a pick and carried out by a hydraulic clamshell or the like.

On the other hand, a deep foundation excavation work or the like is performed using a full section excavation type deep foundation excavator. The underground is unmanned, and the entire section is continuously excavated by only one operator on the ground. There is also known a method of discharging soil.

[0004]

The blasting method is the most general method, and can be performed at relatively low cost irrespective of the scale of the work. However, due to the vibration and noise caused by the blasting, great care must be taken for the safety of the surrounding residents and surrounding roads.
It also has a negative effect on the surrounding ground. That is, when a construction site is adjacent to a house or road, blasting work cannot be performed.

The construction method using a full-section excavation type deep foundation excavator is not only a labor-saving construction method but also excellent in safety to the surrounding area. However, since the machine itself is expensive and the related equipment also requires a large amount of cost, it cannot be said that this is a general construction method.

Therefore, a technique to be solved in order to eliminate the blasting operation for rock crushing when excavating a deep foundation for forming a pile in the underground rock, improve safety and shorten the construction period by efficient rock crushing. Therefore, an object of the present invention is to solve this problem.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed to achieve the above object. In a deep excavation method in which a pile is formed in underground rock, the pile is formed vertically from the ground surface. After drilling a small-diameter pre-drilling hole in the center at the length of the pile, a plurality of perforations are vertically provided by a boring machine in the rock between the outer diameter of the pile and the outer diameter of the pre-drilled hole, An object of the present invention is to provide a deep foundation excavation method for a bedrock in which a rock is crushed by an expansion pressure generated by a reaction with water by filling an expansive material mixed with or absorbed with water in a perforated portion.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 shows a construction site where a deep foundation pile 6 is constructed.
a is newly installed via the bridge 4 on the abutment 5. The deep foundation pile 6 is formed by excavating from the ground surface 2 so as not to affect the adjacent road 1 during construction, and thereafter, a plurality of the deep foundation piles 6 are used to perform mountain retaining work. The anchoring work is carried out by a fixing bracket 20 on a support plate 19 on a fixing pedestal 18 supporting a ground anchor 17 and a PC steel material 16 which are obliquely driven into the ground at the upper and middle portions of the deep foundation pile 6. Do it.

On the other hand, as a result of a geological survey of the construction site of the deep foundation pile 6, granite diorite B was found to be 7 m or less from the ground surface 2,
Manual excavation is a very difficult bedrock, and it is not possible to break the bedrock by blasting work for the safety of the adjacent road. Reference numeral 3 denotes a cut surface for construction of the attachment road 1a.

Next, the order of forming the deep foundation pile 6 will be described with reference to FIGS. In FIG. 2, A indicates the earth and sand portion, and B indicates the bedrock portion of the granodiorite described above. First, a crawler crane 12 is placed at the center of the formation position of the circular deep foundation pile 6 from the ground surface 2.
A vertically excavated circular hole 8 is formed by the town-the-hole hammer 14 suspended on the crane hook 13 of the deep foundation pile 6.
Excavate for the length of The outer diameter 6a of the deep foundation pile 6 is 2
m, the outer diameter of the drill hole 8 is 600 mm.

The excavation hole 8 serves as an open surface for crushing the bedrock B described later. The earth removal in the excavation hole 8 is continuously performed by a telescopic device 15 suspended from the crane hook 13. In addition, the cylindrical widening excavation from the outer diameter of the preceding excavation hole 8 of the earth and sand portion A to the outer diameter of the deep foundation pile 6 is performed by the crawler crane 12 or manually, and as the excavation progresses, the ground surface 2 The steel liner plates 7 of the segment type to be carried into the cylinder are sequentially assembled into a cylindrical shape by manual labor and temporarily laid.

Next, a method of crushing the bedrock B when the stratum changes from the soil A to the bedrock B will be described. First, a drilling position is determined on a plane (FIG. 3) of a rock part B shown in FIG. 4 according to a crushing plan, marking is performed, and a plurality of drilling parts 9, 9,... Are provided vertically by a drilling machine (not shown). In the illustrated example, nine perforations 9, 9,... On the outer periphery located near the outer diameter 6a of the deep foundation pile 6, and five perforations 9, 9,. Are provided at intervals of about 600 mm. The bit diameter of the drilling machine is 32 mm and the drilling length is about 1 m. The size of the perforated portions 9, 9... And the interval between the perforated portions 9, 9,... Are appropriately determined according to the condition of the bedrock B, etc. However, if the interval between the perforated portions 9, 9,. It is too expensive, and the use amount of the expanding material 10 described later increases, which is uneconomical.

Next, as shown in FIG. 4, a predetermined amount of the expanding material 10 mainly composed of an inorganic compound mainly composed of quicklime and silicate is mixed with water by a hand mixer (not shown) or water is absorbed. The perforated portions 9, 9,... Are filled with the expanded material 10 up to the hole. After the filling is completed, the holes are sequentially covered with the protective sheet 11 and cured. The curing time is at least three hours after the filling of the expanding material 10, but is appropriately determined according to the condition of the bedrock B. During the curing, the rock B is fractured by the expansion pressure (50 N / mm ² or more) generated by the reaction between the expanding material 10 and water, thereby cracking the rock B.

The crushing of the bedrock B by the expansive material 10 can be performed quietly with little vibration and noise and no stepping stones.
Further, the excavation hole 8 effectively functions as an open surface accompanying the crushing of the bedrock B, and promotes crushing. After the curing is completed, the cracked bedrock B is secondarily crushed by a breaker or a pick hammer (not shown), divided into small pieces, and transported to the ground surface 2 by the telesco 15. Further, after the liner plate 7 is attached to the outer diameter 6a of the deep foundation pile 6, the deep foundation pile 6 is formed by repeatedly crushing the lower rock B. Thus, the construction of the deep foundation pile can be performed safely without performing the blasting operation.

It should be noted that the outer diameter of the deep foundation pile 6, the outer diameter of the excavation hole 8, the size, the number, the length of the perforated portions 9, 9,... , Depending on the design of the deep foundation pile and the state of the bedrock B. Thus, the present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0016]

According to the present invention, a drilling hole having a small diameter is provided at the center of a deep foundation pile in advance, so that the surface becomes an open surface for the expansion pressure of the expanding material to be filled into the rock, and the rock crushing operation can be easily performed. . Furthermore, since the rock surface is efficiently arranged with a plurality of perforations to fill the expansive material and the rock is gently crushed, there is no need to consider noise and safety as in conventional blasting work, making it extremely easy and reliable. Can be constructed. Therefore, the invention has a remarkable effect, such as greatly shortening the construction period and contributing to a reduction in construction costs.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is an explanatory view showing a place where a deep foundation pile is constructed.

FIG. 2 is a longitudinal sectional view of constructing a pre-drilling hole of a deep foundation pile.

FIG. 3 is a plan view showing a perforated portion of a rock part.

FIG. 4 is a sectional view taken along line XX of FIG. 3;

[Explanation of symbols]

 2 Surface 6 Pile 6a Outer diameter of pile 8 Drilling hole 9 Drilled part 10 Expansive material B Rock

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoichi Hiroshima 26-20 Tatemachi, Aoba Ward, Sendai City, Miyagi Prefecture Inside the Kumagaya Gumi Tohoku Branch (72) Inventor Shinji Ishikawa 26-20 Tatemachi Aoba Ward, Sendai City, Miyagi Prefecture No. F-term in the Kumagaya Gumi Tohoku Branch (reference) 2D046 CA01

Claims (1)

[Claims] In a deep foundation excavation method for forming a pile in underground rock, a small diameter advance drilling hole is excavated at the center of the pile vertically from the surface of the ground for the length of the pile, and then the pile is excavated. A plurality of perforated portions are provided vertically by a drilling machine on a bedrock between an outer diameter and an outer diameter of the preceding excavation hole, and the perforated portion is filled with an expansive material mixed with or absorbed with water to form a hole with water. A deep foundation excavation method in rock, characterized in that the rock is crushed by an expansion pressure generated by a reaction.