Pile driving and extraction method for dealing with nearby buried objects

Abstract

A pile driving and extraction method that can be used in locations close to buried objects, eliminating the need to expose buried objects or conduct test excavations before driving piles, such as those used in the parent pile and horizontal sheet pile method, into the ground. [Solution] When driving a pile into the ground near a buried object, a casing 5 made of steel pipe is buried in the soil while breaking up the ground with water sprayed from a water jet nozzle 4 located at the tip of the casing 5, the soil and sand inside the casing 5 that has been stirred by the water jet is removed to the surface using a vacuum, the casing 5 is inserted into the soil to a predetermined depth, an H-shaped steel 8 serving as a pile is erected inside the casing 5, the gap between the casing 5 and the H-shaped steel 8 is filled with backfill material 10, the casing 5 is then pulled out, and the pulling out is stopped when the bottom end of the casing 5 is a certain length below the bottom end of the buried object 11, leaving part of the bottom of the casing 5 in the soil.

Description

[Technical Field]

[0001] This invention relates to a method for driving or extracting earth retaining piles to prevent the collapse of soil and sand in the ground surrounding an excavation hole when excavating from the ground surface to construct an underground structure such as a manhole underground. [Background technology]

[0002] When constructing underground structures such as manholes underground, earth retaining work (using the pile and horizontal sheet pile method, steel sheet pile method, etc.) is carried out to prevent landslides in the surrounding ground, and designated locations are excavated.In places such as cities where buried objects are congested, structures are relatively shallow, and the groundwater level is low, the pile and horizontal sheet pile method is often used.

[0003] Patent document 1 shows an example of a parent pile and horizontal sheet pile construction method for earth retaining work, which is composed of multiple parent piles erected in the ground at predetermined intervals and multiple horizontal sheet piles inserted sequentially between these parent piles.

[0004] To explain in more detail, a commonly known method for constructing retaining walls during excavation work involves driving H-shaped steel beams called parent piles at equal intervals along the excavation line, and then inserting multiple cross-sheet piles horizontally between the parent piles as the excavation progresses to create the retaining wall. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-81338 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] When driving piles using the above-mentioned parent pile and horizontal sheet pile method, the piles must be driven in a location that avoids buried objects underground and does not affect them. Considering the impact on buried objects, a distance of about 50 cm is generally required between the buried objects and the piles. However, in urban areas where buried objects are congested and the required distance cannot be achieved, the buried objects are exposed and the piles are driven while visually inspecting their condition.

[0007] However, excavation work is required to expose buried objects when driving piles. Also, buried objects in relatively shallow locations can be identified by test digging or by digging a sheet before driving piles, but buried objects in deeper locations cannot be identified by test digging or the like, and there is a risk that the buried objects will be damaged by driving piles.

[0008] In order to solve the above-mentioned problems, the present invention aims to provide a pile driving and extraction method that can be used in areas close to buried objects and that does not damage nearby buried objects when driving piles, such as those using a parent pile horizontal sheet pile method, into the ground. [Means for solving the problem]

[0009] The invention of claim 1 is a pile driving method in which, when driving a pile into the ground, a casing made of steel pipe is buried in the soil while breaking up the ground with water sprayed from a water jet nozzle located at the tip of the casing, the soil and sand inside the casing that has been stirred by the water jet is removed to the surface using a vacuum, the casing is inserted into the soil to a specified depth, and the pile is erected inside the casing, the gap between the inner circumference of the casing and the outer circumference of the pile is filled with backfill material made of cement solidification material, sand, soil, etc., and then the casing is pulled out.

[0010] In addition, the invention of claim 2 is a pile driving method in which, when driving a pile into the ground near a buried object, a casing made of a steel pipe is buried in the soil while breaking up the ground with water sprayed from a water jet nozzle located at the tip of the casing, the soil and sand inside the casing that has been stirred by the water jet is removed to the surface by vacuum, the casing is inserted into the soil to a predetermined depth, and a pile is erected inside the casing, the gap between the casing and the pile is filled with backfill material made of sand, soil, etc., and then the casing is pulled out, and the pulling out is stopped when the bottom end of the casing is a certain length below the bottom end of the buried object, and a part of the bottom of the casing is left in the soil.

[0011] In addition, the invention of claim 3 is a pile driving method as described in claim 2, in which, during retaining work, half of the casing left in the ground on the excavation surface side is cut and peeled off, and the half casing is left in the ground.

[0012] The invention of claim 4 is a pile extraction method as described in claim 2 or 3, in which, when extracting a pile driven into the ground, the pile is first extracted from the ground and then the casing is extracted. [Effects of the Invention]

[0013] According to the inventions of claims 1 to 3, the casing is inserted into the ground prior to the pile driving, so the condition of the ground at the pile driving location, especially the presence or absence of buried objects, can be confirmed, and damage to nearby buried objects due to pile driving can be avoided. In addition, the casing is inserted into the ground while breaking up the soil using a water jet, so buried objects can be easily detected and there is no risk of damaging them.

[0014] Furthermore, according to the inventions of claims 2 and 3, the casing remains in the ground facing the buried object even after the pile is driven in, so that the buried pile can be pulled out without affecting the buried object.

[0015] Furthermore, according to the invention of claim 3, the casing is left in a split state, so that when retaining earth work is carried out, sheet piles can be connected between adjacent piles, and the casing left in the ground does not get in the way.

[0016] Furthermore, according to the invention of claim 4, the pile is surrounded by a casing when it is pulled out, so that buried objects are not affected and there is no need to expend time and effort on tasks such as exposing the buried objects. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a vertical cross-sectional view showing a step 1 of embedding a casing into the ground in a pile driving method according to a first embodiment of the present invention. [Figure 2] 1 is a vertical cross-sectional view showing a step 2 of embedding a casing into the ground in the pile driving method according to the first embodiment of the present invention. [Figure 3] 1 is a vertical cross-sectional view showing a process of driving a pile into an embedded casing in a pile driving method according to a first embodiment of the present invention. FIG. [Figure 4] 1 is a vertical cross-sectional view showing a step of filling a gap between an embedded casing and a pile with backfill material in a pile driving method according to a first embodiment of the present invention. FIG. [Figure 5] 1 is a vertical cross-sectional view showing a process of extracting an embedded casing from the ground in the pile driving method according to the first embodiment of the present invention. FIG. [Figure 6] 1 is a vertical cross-sectional view showing a process of water tightening while pulling out an embedded casing from the ground in the pile driving method according to the first embodiment of the present invention. FIG. [Figure 7] 1 is a vertical cross-sectional view showing a process of repeatedly pulling out an embedded casing from the ground and filling it with backfill material in a pile driving method according to a first embodiment of the present invention. FIG. [Figure 8] 1 is a vertical cross-sectional view of a state in which an embedded casing has been pulled out and a portion of it has been left in place in a pile driving method according to a first embodiment of the present invention. [Figure 9]1 is an enlarged vertical cross-sectional view of a state in which a buried casing has been pulled out in the pile driving method of the first embodiment of the present invention, with a portion of the casing left in the ground. [Figure 10] 1 is an enlarged plan view showing the state in which an embedded casing is pulled out in the pile driving method of the first embodiment of the present invention, a portion of which is left in the ground, and the casing is cut in half and pulled out. [Figure 11] FIG. 1 is an enlarged plan view showing a method for creating an earth retaining wall using a pile and horizontal sheet pile method after driving piles in the pile driving method according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] (Embodiment Example 1) A pile driving method according to a first embodiment of the present invention will be described with reference to FIGS.

[0019] First, as shown in Figure 1, a water jet nozzle 4 attached to the end of a water jet hose 3 extending from a water jet pump 2 mounted on the platform of a work vehicle 1 placed on the ground is attached to the end of a casing 5 at the site where the pile will be driven. Water is sprayed from the water jet nozzle 4 to break up the ground, and the casing 5 is then buried in the ground using a steel pipe press-in / pulling machine 14. The casing 5 is made of a threaded steel pipe. The water jet disturbs the soil near the end of the casing 5, discharging the wet soil and sand through the casing 5 to the ground via a vacuum hose 6 attached to the end of the casing 5. The vacuum hose 6 is attached to a vacuum truck 7 on the ground. During this process, the inside of the casing 5 is inspected visually by workers or photographed with a CCD camera (not shown). In this manner, the casing 5 is buried in the ground, adding new pieces of material as shown in Figure 2.

[0020] After the casing 5 is inserted into the ground, an H-beam 8 serving as a pile is erected within the casing 5 as shown in FIG. 3. To do this, the H-beam 8 is inserted into the casing 5 while being suspended by a crawler crane 9 as shown in FIG. 3. After the H-beam 8 is erected, a backfill material 10 such as cement solidification material, sand, soil, etc. is inserted and filled into the gap between the inner periphery of the casing 5 and the outer periphery of the H-beam 8 as shown in FIG. 4. Then, as shown in FIG. 5, the casing 5 is extracted from the ground using the steel pipe press-in / extraction machine 14, and at the same time, water tightening is performed as shown in FIG. 6. The extraction of the casing 5 and the filling of the backfill material 10 are repeated as shown in FIG. 7. In this manner, the casing 5 is extracted from the ground, and the H-beam 8 is buried and supported in the ground.

[0021] When the buried H-shaped steel 8 is to be removed, it is pulled out of the ground using a pile extraction device (not shown), and the resulting pile holes are backfilled with the backfill material 10 each time.

[0022] Furthermore, if there is a buried object 11 close to the location where the H-shaped steel 8 is buried, a part of the casing 5 is left in the ground after backfilling is completed, as shown in Fig. 8. To do this, as shown in Fig. 9, the casing 5 is pulled out from the ground, but the pulling out of the casing 5 is stopped when the distance L between the bottom end of the casing 5 and the bottom end of the buried object 11 reaches a length of about 30 to 50 cm, and in this state, a part of the casing 5 is left in the ground.

[0023] In this way, when a part of the casing 5 is left around the H-shaped steel 8, when removing the H-shaped steel 8, the H-shaped steel 8 is first pulled out from the ground using a pile extraction device, and then the casing 5 is pulled out, and the resulting pile hole is backfilled with the backfill material 10 each time.

[0024] Furthermore, to create an earth-retaining wall using the H-shaped steel beams 8 by the parent pile and horizontal sheet pile method, a plurality of H-shaped steel beams 8 are buried at equal intervals as described above, and as shown in Figure 10, one side of the excavation line A connecting these plurality of H-shaped steel beams 8 is excavated, exposing half of the casing 5 of each H-shaped steel beam 8 on the excavation face side in the excavation hole 12, and cutting the casing 5 so that its cross section is semicircular. Then, as shown in Figure 11, horizontal sheet piles 13 are fitted into each of the adjacent H-shaped steel beams 8 surrounded by the half casing 5a to create an earth-retaining wall.

[0025] When the retaining wall is to be removed after the buried object construction work is completed, the cross-sheet piles 13 are removed, and after each H-shaped steel 8 is pulled out, the half casing 5a is removed.

[0026] In this way, if there is a buried object 11 in the ground near where the H-shaped steel 8 is buried, the H-shaped steel 8 is erected inside the casing 5 so as not to affect the buried object 11, and when removing the H-shaped steel 8, first the H-shaped steel 8 is pulled out from the ground, and finally the half casing 5a is pulled out, thereby protecting the buried object 11 and preventing damage to the ground near the buried object 11.

[0027] In the first embodiment, the piles for constructing the earth retaining wall using the parent pile and horizontal sheet pile construction method are described, but the pile driving and extraction method is not limited to the piles used in the parent pile and horizontal sheet pile construction method. Furthermore, the piles are not limited to H-shaped steel. [Explanation of symbols]

[0028] Drilling line A 1 Work vehicle 2 Water jet pump 3 Water jet hose 4 Water jet nozzle 5 Casing 5a Half Casing 6 Vacuum hose 7 Vacuum truck 8 H-beam 9 Rough terrain crane 10 Backfill material 11 Buried objects 12 Cutting hole 13 Horizontal sheet pile 14 Steel pipe press-fitting and drawing machine

Claims

1. A pile driving method characterized by the steps of: when driving a pile into the ground, burying a casing made of steel pipe in the soil while breaking up the ground with water sprayed from a water jet nozzle located at the tip of the casing; removing the soil and sand inside the casing that has been agitated by the water jet to the surface using a vacuum; inserting the casing into the soil to a predetermined depth and setting the pile inside the casing; filling the gap between the inner circumference of the casing and the outer circumference of the pile with backfill material consisting of cement solidification material, sand, soil, etc.; and then pulling out the casing.

2. This pile driving method is characterized by the steps of: when driving a pile into the ground near a buried object, burying a casing made of steel pipe in the soil while breaking up the ground with water sprayed from a water jet nozzle located at the tip of the casing; removing the soil and sand inside the casing that has been agitated by the water jet to the surface using a vacuum; inserting the casing into the soil to a predetermined depth and setting the pile inside the casing; filling the gap between the casing and the pile with backfill material made of sand, soil, etc.; and then withdrawing the casing; stopping the withdrawal when the bottom end of the casing is a certain distance below the bottom end of the buried object, and leaving part of the bottom of the casing in the soil.

3. A pile driving method as described in claim 2, characterized in that, when constructing a retaining wall, half of the casing left in the ground on the excavation surface side is cut and peeled off, and the half casing is left in the ground.

4. 4. The pile extraction method according to claim 2 or 3, wherein when extracting a pile driven into the ground, the pile is first extracted from the ground and then the casing is extracted.

Images