JPH0536565B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a shallow ground improvement method.

[Conventional technology]

In soft ground locations, when there is no ground bearing capacity for the structure, conventional methods such as earth displacement method, pile foundation method, chemical injection method, consolidation method (preload method,
Soft ground is being strengthened using construction methods such as the sand compaction method and water drainage method.

[Problem that the invention seeks to solve]

However, considering the recent construction environment, these construction methods have the following problems.

In other words, with the replacement earth construction method, the impact of excavation on surrounding facilities (houses, etc.) due to ground subsidence, the difficulty of disposing of the excavated soil, the increase in construction costs due to earth retention work, and the large amount of soil purchased for replacement soil, resulting in high construction costs. There are problems such as.

Pile foundation construction methods are often vibration-free and noise-free due to the construction environment, making it difficult to dispose of waste soil, causing water pollution due to the use of hole wall protection agents, and taking reaction force only with piles. Therefore, there are problems such as large-scale construction and relatively high construction costs.

The chemical injection method contaminates groundwater quality, the amount of injection is not clear, and the ground improvement effect is unreliable.
There are problems such as high construction costs.

In the pre-load construction method, a large amount of soil is required for pre-filling, and it takes time to consolidate.On the roadside, when pre-filling, it is necessary to include adjacent land, and it is necessary to include the adjacent land in areas where facilities (houses) etc. are close together. However, there are problems such as impossibility of construction.

In the sand compaction method, sand is injected into the soft ground, which causes consolidation of the surrounding ground, but the sand pile itself does not have much bearing capacity, so the ground improvement is based on the degree of consolidation itself, and the overall Ground bearing capacity cannot be expected unless compaction within the area is taken into account; construction equipment is large-scale; therefore, it is difficult to employ unless the construction scale is large, and construction costs are high;
Further, there are problems such as vibrations occurring when sand is press-fitted.

Drainage methods involve pumping up groundwater to promote consolidation settlement, which takes time to become effective, affects surrounding facilities (houses, etc.), and has problems with the treatment of pumped water.

[Purpose of the invention]

The present invention has been made to solve the above problems, and an object of the present invention is to provide a shallow ground improvement method that can sufficiently strengthen soft ground without causing environmental destruction.

[Means for solving problems]

The shallow ground improvement method according to the present invention places a weight on the soft ground, has a drill blade on the outer periphery, and drives a conical auger formed at the tip of the push pipe into the shallow part of the soft ground. While inserting the auger into the ground, the weight prevents the dissipation of stress due to the swelling of the topsoil due to the insertion of the auger, and forms a hole with a consolidated periphery, and after the auger reaches a predetermined depth, the auger is inserted into the ground. While pulling out the pipe, filler material is press-fitted into the hole from the tip of the push-in pipe, and a friction pile is formed so that the amount of settlement displacement is uniform with the surrounding ground, thereby creating an uneven settlement prevention layer. be.

[Effect]

In the present invention, first, a weight is placed on soft ground, and then a conical auger, which has drill wings on the outer periphery and is formed at the tip of a push pipe, is placed in a shallow part of the soft ground. While inserting the auger into the hole, the weight prevents the dissipation of stress due to the heaving of the topsoil due to the insertion of the auger, and forms a hole with a compacted periphery. After this hole reaches a predetermined depth, while pulling out the auger,
Press the filling material into the hole from the tip of the push pipe,
Friction piles are formed so that the amount of subsidence is uniform with the surrounding ground to create an uneven subsidence prevention layer, and it is possible to form a ground that can sufficiently withstand overburden loads.

〔Example〕

Hereinafter, details of the present invention will be described with reference to an embodiment shown in the drawings.

Figure 1 shows an example of an apparatus used in the shallow ground improvement method according to the present invention, and in the figure, reference numeral 1
1 shows a base machine having a main pillar 13. A hopper 17 formed at the upper end of the push-in pipe 15 is suspended from the upper end of the main column 13 by a hanging wire 19. The push-in pipe 15 is vertically movable by a cylinder 21 arranged on the main column 13.

Thus, in the ground improvement device of this embodiment, a screw conveyor 25 rotated by a drive device 23 is disposed within the push pipe 15. A valve 27 that opens from the inside to the outside is arranged at the tip opening of the push-in pipe 15. An auger 29 is arranged at the tip of the push pipe 15. This auger 29 has a cylindrical portion 31 as shown in FIG.
and a conical portion 3 formed above and below this cylindrical portion 31.
3,35. Lower cone part 3
5 has a drill blade 37 that converts the rotational force of the auger 29 into propulsive force, and a drill blade 38 is formed in the upper conical portion 33. In addition, the push-in pipe 15
is rotatable by a rotary power head 39.

3 and 4 show a weight 41 that prevents the topsoil from rising when the auger 29 is pushed into soft ground 40.
is constructed by connecting half bodies 43 and 45 with a bolt 47, and an auger 29 is attached to the center of the weight 41.
A through hole 49 is formed to insert the.

Using the ground improvement device configured as described above, the shallow ground improvement method of the present invention is carried out as described below.

That is, first, as shown in FIG. 5, a weight 41 is placed on the soft ground 40, and the auger 29
Dissipation of stress due to heaving of topsoil when pushed into soft ground 40 is prevented. Thereafter, the push-in pipe 15 is inserted into the soft ground 40 by the cylinder 21 while being rotated by the rotary power head 39. At this time, the conical portion 35 of the auger 29 forms a hole 51 whose periphery is compacted. Further, since the drill blades 37 are arranged on the auger 29, the rotational force of the auger 29 becomes a thrust, making it easy to insert the push pipe 15 into the soft ground 40, and making it possible to downsize the base machine 11. After this hole 51 reaches a predetermined depth,
A valve 27 formed at the tip of the push-in pipe 15 is opened. After this, as shown in Figure 6, the auger 2
The screw conveyor 25 is rotated while pulling out the screw 9 while applying reverse rotation, and the filling material (for example, a mixture of cement and sand) 53 in the hopper 17 is pushed through the hole from the tip of the push pipe 15 by the screw conveyor 25. 51. Also, during this pulling out, the auger 29 is rotated in the opposite direction.
The upper conical portion 33 forms a consolidated layer again around the soft ground 40, thereby preventing the ground around the hole wall from loosening. Then, after pulling out the push-in pipe 15, by leaving it for a certain period of time, the filling material 53 hardens, and a friction pile 55 as shown in FIG. 7 is formed.

That is, in the ground improvement method configured as described above, the conical auger 29 is inserted into the soft ground 40 to form the hole 51 with its surroundings consolidated, and the filling material 53 is inserted into the hole 51. Since the friction pile 55 is press-fitted, the surrounding ground and the friction pile 55 share different loads, but the amount of settlement displacement is uniform, and it is possible to form a ground that can sufficiently withstand the overburden load. can.

In addition, in the ground improvement device configured as described above, the screw conveyor 25 is installed inside the push pipe 15.
At the same time, a valve 27 that opens from the inside to the outside is placed at the tip opening of the push-in pipe 15.
The filling material 53 can be easily supplied into the hole 51 when the auger 29 is pulled out. Further, the auger 29 is composed of a cylindrical part 31 and conical parts 33 and 35 formed above and below this cylindrical part 31, and the lower conical part 3
5 is provided with a drill blade 37 that converts the rotational force of the auger 29 into propulsive force, the auger 29 can be easily inserted into the ground while forming a compacted layer around the hole 51.

Furthermore, according to the shallow ground improvement method configured as described above, excavated soil and waste soil are not generated, so that the treatment of these soils is not necessary. There will be no impact on surrounding buildings as there will be no excavation. No water pollution. By consolidating the hole wall, the ground around the pile is consolidated and the bearing capacity is increased. For example, sufficient vertical reaction force can be obtained by making mortar piles, and resistance to buckling can be increased by incorporating short iron wires. It has advantages such as vibration-free and noise-free construction method.

In the present invention, the friction pile refers to a pile installed in an uneven settlement prevention layer in a soft ground layer, as shown in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the auger is
While inserting into the shallow part of the soft ground,
The weight prevents the dissipation of stress caused by the heaving of the topsoil due to the insertion of the auger, and at the same time, a compacted hole is formed around the periphery, and after this hole reaches a predetermined depth, while pulling out the auger, the tip of the push pipe is This method creates an uneven settlement prevention layer by press-fitting filling material into the hole and forming a friction pile that makes the amount of settlement uniform with the surrounding ground.
It becomes possible to improve the ground around the friction pile, and the soft and shallow ground can be consolidated around it by the action of the friction pile, making it a reinforced ground that is integrated with the friction pile, and creating an uneven settlement prevention layer.

As a result, it becomes possible to use the soft ground itself as supporting ground.

[Brief explanation of the drawing]

Fig. 1 is a side view showing one embodiment of the soil improvement device of the present invention, Fig. 2 is a partial vertical cross-sectional view showing details of the auger part in Fig. 1, and Figs. 3 and 4 are top views of the weights. The drawings and side views, and FIGS. 5 to 7 are explanatory diagrams showing one embodiment of the shallow ground improvement method of the present invention, and FIG. 8 is an explanatory diagram of a friction pile in the present invention. 15...Push pipe, 25...Screw conveyor,
27...Valve, 29...Auger, 31...Cylindrical part, 33,
35... Conical part, 37, 38... Drill blade, 51... Hole, 53... Filling material, 55... Friction pile.

Claims (1)

[Claims] 1. Place a weight on soft ground, insert a conical auger with drill wings on the outer periphery and formed at the tip of a push pipe into the shallow part of the soft ground, and insert the auger into the soft ground. The weight prevents the dissipation of stress due to the swelling of the topsoil due to insertion, and also forms a hole with its periphery consolidated, and after the hole reaches a predetermined depth, while pulling out the auger, the weight is removed from the tip of the push pipe. A shallow ground improvement method characterized by creating an uneven subsidence prevention layer by press-fitting filling material into the hole and forming a friction pile whose subsidence displacement is uniform with the surrounding ground.