JPH04309617A - Method for improving foundation ground and device therefor - Google Patents

Abstract

PURPOSE:To work a strong ground layer in wide area easily by drilling core holes in a temporary foundation ground, building cement milk core materials, and inserting steel columns into the core materials as core columns. CONSTITUTION:An work device in which an excavating edge is provided at the top of its head and an agitating edge is mounted just above the excavating edge is set at a specified ground a, and the ground is excavated to drill a core hole b. After the hole is drilled to a specified depth, a cement milk C is filled through a cement milk injecting hole at the top of the device into the hole, and the cement milk is agitated by means of the agitating edge. The device is then raised and a cement milk column d is built up. Before the cement milk is solidified, steel materials of proper forms such as H, round, triangle, square, etc., are inserted into their respective cement columns d as core members to build a strong improved ground layer under the ground. Also, a nodular column P, which is formed by installing multiple nodes f integrally and projectedly on the column surface, can be pressed for installation into the cement milk column d instead of the core material.

Description

[Detailed description of the invention] [Industrial application field]

[0001] This invention is an improvement of foundation ground, which aims to safely and reliably create a strong foundation ground suitable for numerical values over a wide area, regardless of the condition of the foundation ground for construction, such as unstable soft ground. It concerns construction methods and construction equipment.

[Conventional technology]

[0002] For example, as shown in Fig. 4, in the case where the foundation ground has been prepared with an N value of 50 or more, there is no particular need for ground improvement, but in a low ground layer where the N value is 50 or less, strong ground improvement is required. It is common sense to drive support piles for this purpose. Recently, in order to obtain even greater bearing capacity, the industry has developed a ground improvement method in which pile pillars made of silt and clay are constructed underground as supporting materials.

[Problem to be solved by the invention]

However, in the case where the N value is around 50, that is, in the middle layer, even if support piles are driven due to geological conditions, they will be unbalanced, so a large number of strong support piles are required, and it is difficult to securely cover a wide area. Not only is it difficult to improve the ground, but the ground improvement using silt and clay materials has the serious drawback of being weak against lateral bending forces, and especially when excavating pile holes. There was also a problem with how to dispose of soil.

[Means to solve the problem]

This invention has focused on the above-mentioned problems and has made it possible to extremely easily and reliably construct a wide range of ground layers having a strength of N value of 50 or more without requiring support piles in the middle layer of the ground. Several core holes are dug at appropriate intervals depending on the strength of the ground in the area targeted for improvement, that is, temporary foundation ground, and cement milk is used as a core material in the core holes. By constructing core pillars underground as improved ground, it is possible to construct a strong foundation with a large diameter in the middle layer of any ground layer.

[0005] Furthermore, in the present invention, when constructing the core pillar, several core holes are previously drilled in the temporary foundation ground layer as described above, and a large number of collar joints are installed in the core hole. It is also possible to easily construct a strong, wide-area ground layer that integrates the entire underground by driving the attached knotted columns at appropriate intervals.

[0006] As the above-mentioned means, as described in claim 3, a digging blade is provided at the tip of the head, and one or more disturbance blades having a length approximately the same as the diameter of the head are disposed above the digging blade. At the same time, the entire upper head surface of the above-mentioned disturbance blade is formed into a compacted earth surface with an appropriate inclination angle, and the action of the compacted earth surface firmly presses the circumferential wall of the hole at the same time as the hole is being dug, and forms a temporary foundation ground. Construction of the foundation ground by making sure to drill a core hole that will not cause landslides without soil removal, and at the same time filling the hole with cement milk to construct an ideal cement milk pillar underground. The aim is to provide the equipment.

[Effect]

[0007] The present invention has the above-mentioned structure, in which the construction device according to claim 3 is attached to a drilling machine and is driven to drill a large number of core holes at appropriate locations in the temporary ground. Simultaneously with the excavation, the peripheral wall of the borehole is firmly compressed by the action of the compacted earth surface of the device, and the excavation work continues to a predetermined depth. When the core hole excavation reaches a predetermined depth, the excavation is stopped, cement milk is injected from the tip of the device, and while it is stirred by the rotating action of the stirring blade, the entire device mechanism is pulled out to the ground and buried in large quantities underground. concrete milk pillars will be poured. Therefore, when the cement milk column is in a state before hardening, a steel material of an appropriate shape such as H steel or round steel is press-inserted as a core material, and after a certain period of time, the cement milk becomes integrated with the surrounding soil together with the core material. By solidifying and hardening, it is possible to easily create a solid intermediate ground between the ground layer and the core pillar. It goes without saying that a stronger and more effective ground layer can be created by intensively constructing the above-mentioned core material in areas where loads are particularly required, such as areas with low numerical values as shown in the chart in Figure 4. do not have. In addition, in this invention, construction is carried out using a knotted column having a large number of knots formed in the core material, so that the cement milk charged into the core hole during pouring is naturally distributed between each knot. It is also possible to easily and reliably create a wide-area ground layer that can sufficiently handle bending loads and the like by inflowing and filling the ground.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a construction device used in the present invention, in which several digging blades 2 are disposed at the tip of a head 1 whose overall shape is approximately conical. One or several disturbance blades 3 having a blade length approximately the same as the width R are attached depending on the quality of the excavated soil, and a pressure having a constant inclination angle X is attached to the upper conical surface portion of the head 1. A soil surface 4 is formed and provided. Further, the pressed earth surface 4 is formed with an arbitrary slope of steepness or steepness depending on the geology or the like. 5 is an auger rod of an appropriate length, the upper part of which is connected to the power and is attached to the drilling machine so as to be movable up and down. A cement milk feeding pipe 6 is provided vertically inside the shaft of the auger rod 5, and is configured to inject and fill the hole with cement milk from a cement milk spouting hole 7 at the tip of the head.

[0009] The ground improvement method according to the present invention is shown in Fig. 2 below.
To explain this using an example of construction, (1) the device is set on a predetermined ground a, and a hole is dug in the ground by rotational driving. (2) Due to this rotational drive, the ground is excavated by the action of the digging blade 2 and the disturbance blade 3 to a predetermined depth. Further, the compacted soil surface 4 of the device, which descends simultaneously with the excavation described above, excavates while strongly compressing the circumferential wall of the surrounding hole, thereby drilling a core hole b having a strong circumferential wall in the ground. (2) When the excavation reaches a predetermined depth, the excavation operation is stopped, and the cement milk c is injected into the hole from the cement milk injection hole 7 at the tip of the device, and is stirred and agitated by the agitation blade 3. (2) While continuing the injection of cement milk c and the stirring operation, the entire device is gradually pulled up and removed from the ground from inside the core hole b, and a large-diameter cement milk column d is constructed underground. As described above, a large number of cement milk pillars d are constructed at necessary locations on the ground layer a, and before the milk solidifies, a steel material having an appropriate shape such as H, round, three, square, etc. is placed as a core in each cement milk pillar d. By inserting it as a material, a strong and improved ground layer can be created in the ground. Also, instead of the above core material,
■ Press-fit the jointed pillar P, which has a large number of joints f, f, f integrally protruded at appropriate intervals on the pillar surface, into the cement milk pillar d formed above, and By driving the core pillars up to the point 3A, it is possible to easily create a large-diameter foundation ground by driving a large number of core pillars in the ground layer a, as shown in FIG. 3A. Furthermore, when constructing the above-mentioned jointed pillars, the joint surfaces of the joints f, f, f of each pillar are placed adjacent to each other so that they are in contact with each other as shown in Figure 3B, and the construction is carried out in parallel. It is also possible to easily and reliably create a ground layer over a wide area with a larger diameter.

[0010] In addition, when using this construction method, for example, the foundation arrangement shown in Fig. 5, (1) and (2) is when the entire foundation of a building is to be ground improved, and (3) is when the fabric foundation part of the building is to be improved mainly. When improving the ground in (4) and (5), it is a good idea to install core pillars in parallel around the ground in a fence-like manner and to remove the soil inside, which is suitable for the purpose of construction such as mountain retaining work. The range of possibilities is vast, such as being able to easily and reliably create construction ground at will.

【Effect of the invention】

[0011] As described above, the present invention is achieved by drilling several core holes at appropriate intervals in the temporary foundation ground according to the strength, and constructing a large number of core pillars using cement milk in the core holes. It is possible to extremely easily construct a strong ground layer that can sufficiently withstand load bending, etc., even if it is the ground, and especially in the middle layer, which has been a problem in the past, it is strong enough to perform even better. It is possible to easily and reliably construct a large-scale foundation underground.

Furthermore, due to the action of the sloped soil surface of the construction equipment, the excavated soil is strongly compacted against the peripheral wall of the hole at the same time as the hole is excavated, and this forms a strong compacted layer on the wall surface, and the excavated soil is However, this invention is the most suitable as a construction method that does not require soil removal, as it does not require much soil to be lifted above the ground.

[Brief explanation of drawings]

[Figure 1] Overall diagram of construction equipment,

[Fig. 2] Explanatory diagram showing the state of foundation construction in sequence,

[Figure 3]
Same as above, construction completion drawing,

[Figure 4] Relationship diagram between soil quality, depth, and created ground;

FIG. 5 is a plan view showing various construction examples of the foundation structure.

[Explanation of symbols]

1 Head 2　Drilling blade 3 Disruption blade 4　Pressed earth surface c Cement milk d Cement milk pillar P Knotted pillar

Claims (3)

[Claims] Claim 1: Several core holes are drilled at appropriate intervals in the ground of the area targeted for improvement, that is, temporary foundation ground, depending on the strength, and a core material made of cement milk is placed inside the core holes. A method for improving foundation ground, characterized by constructing it as an improvement material and creating a large-diameter foundation underground by inserting a steel column of an appropriate shape into the core material as a core column. [Claim 2] Several core holes are drilled in the temporary foundation ground according to claim 1 using a boring machine, and a knotted column having a large number of collar joints is installed in the core holes. A foundation soil improvement method characterized by attempting to create a large-diameter foundation underground by pouring concrete at appropriate intervals. 3. A digging blade is provided at the tip of the head, and one or more disturbance blades having a diameter approximately the same as the head diameter are disposed above the digging blade, and an appropriate blade is provided on the upper head surface of the disturbance blade. A foundation ground construction device characterized by forming and providing a substantially conical pressed earth surface having an inclination angle.