A construction method for bored piles in karst areas

Abstract

This invention discloses a construction method for bored piles in karst cave areas, relating to the field of building engineering technology. The method includes steps such as karst cave exploration, drilling, hole cleaning, connecting a steel casing via a positioning mechanism, hoisting the steel casing into the hole, inserting a waterproof membrane, pouring concrete inside the steel casing, removing the positioning mechanism, pouring concrete again inside the hole, and removing the waterproof membrane after the concrete has initially set. This method solves the problem of high construction difficulty for bored piles in karst cave areas and effectively ensures the quality of the bored piles. This invention effectively avoids the impact of karst cave water sources on the construction of concrete piles, and is characterized by low construction difficulty and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically to a construction method for bored piles in karst areas. Background Technology

[0002] Karst primarily refers to the geological processes by which groundwater and surface water chemically dissolve and mechanically erode soluble rocks. The landforms formed by this geological process are internationally known as karst topography. Surface water and groundwater typically have an erosive effect on soluble rocks, resulting in a series of karst landforms of varying shapes and sizes, including underground rivers, karst fissures, sinkholes, funnels, and karst depressions. Because karst phenomena are a typical adverse geological feature, they are widely present in engineering construction, posing significant hazards to building construction. Improper handling during construction often leads to problems such as drill bit loss, stuck drill bits, buried drill bits, and collapses, and can even result in reduced pile foundation bearing capacity and uneven foundation settlement.

[0003] For the construction of karst caves, the common method is to fill the caves with poured concrete to ensure the smooth formation and stability of the piles. However, karst caves are formed by groundwater erosion, and they generally suffer from seepage, with even underground streams flowing through them. A large portion of the poured concrete is likely to be lost, resulting in significant waste and negatively impacting the concrete's strength due to the continuous seepage of water. Furthermore, under such complex and harsh geological conditions, conventional cast-in-place piles need to be improved to enhance structural strength. Summary of the Invention

[0004] This invention provides a construction method for bored piles in karst cave areas. This method can solve the problem of high construction difficulty of bored piles in karst cave areas and can effectively ensure the quality of bored piles.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for constructing bored piles in karst areas includes the following steps:

[0007] Step 1: Conduct a site survey to understand the depth, size, and distribution of underground karst caves, and select suitable drilling locations accordingly;

[0008] Step 2: Insert the steel casing into the soil at the drilling location using a drilling and pulling machine;

[0009] Step 3: Drill holes using a rotary drilling rig with a drill bit. During the drilling process, the excavated soil is transferred to the ground outside the hole opening until the set depth is reached.

[0010] Step 4: Clean the holes;

[0011] Step 5: Connect the top ends of the four steel sleeves through the positioning mechanism to position the four steel sleeves longitudinally. Connect the positioning mechanism through the lifting equipment and hoist the four steel sleeves into the hole.

[0012] Step 6: Guide grooves are provided at both ends of the side wall of the steel sleeve. Waterproof plates are snapped between the adjacent guide grooves of adjacent steel sleeves. The four sets of waterproof plates form a waterproof structure for the pile body to be poured and enclose a first space for pouring the pile. A second space is formed between the waterproof plate and the inner wall of the hole.

[0013] Step 7: Remove the positioning mechanism and pour concrete inside the steel casing; after pouring concrete into the four steel casings, a steel-concrete composite column structure is formed to strengthen the strength of the cast-in-place pile.

[0014] Step 8: Lower the steel cage into the first space and pour concrete;

[0015] Step 9: After the concrete is poured and initially formed, the steel casing is pulled out using a puller.

[0016] Preferably, in step 5, the positioning mechanism includes four positioning blocks, a cross-shaped connecting rod, and a lifting lug. The four positioning blocks are respectively inserted into the top end of a steel sleeve and are detachably and fixedly connected to the steel sleeve. The free ends of the cross-shaped connecting rod are respectively bent downward and fixedly connected to the top end of the positioning block. The lifting lug is fixedly welded to the center of the top end of the cross-shaped connecting rod.

[0017] Preferably, in step 5, the top of the side wall of the steel sleeve is provided with a connecting hole, the outer wall of the positioning block is provided with a threaded hole, and the positioning block and the steel sleeve are fixedly connected by bolts passing through the connecting hole and screwed into the threaded hole.

[0018] Preferably, in step 6, the length of the steel sleeve is consistent with the length of the pile body to be cast in, the guide groove is set along the length direction of the steel sleeve, the top end of the guide groove is flush with the top end of the steel sleeve, and the bottom end is flush with the bottom end of the steel sleeve; the four steel sleeves are evenly distributed around the axis of the pile body.

[0019] Preferably, in step 6, the waterproof membrane includes several waterproof membrane segments. The top and bottom ends of each waterproof membrane segment are provided with a first slot and a second slot, respectively. Adjacent waterproof membrane segments are snapped together through the first slot and the second slot. The left and right ends of each waterproof membrane segment are respectively sealed and slidably connected to the guide grooves of the corresponding steel sleeves. Several waterproof membrane segments are stacked sequentially between the adjacent guide grooves of adjacent steel sleeves. The snapped waterproof membrane is coaxial with the pile body.

[0020] Preferably, in step 6, the inner surface of the guide groove, the inner surface of the first slot or the second slot are respectively provided with elastic rubber pads, and the sealing between the left and right ends of the waterproof membrane segment and the corresponding guide groove, as well as the sealing between the interlocking first slot and the second slot, are achieved by the elastic rubber pads.

[0021] Preferably, step 9 further includes removing the waterproof membrane after the initial setting of the concrete in the pile body. The outer surface of each segment of the waterproof membrane is provided with a hanging ring for connecting to a hook. A steel wire rope is connected to the lifting equipment, and the steel wire rope is connected to the hook. The hook moves downward along the second space and connects to the hanging ring. In this way, the waterproof membrane is pulled out segment by segment. After being pulled out, the soil excavated from the borehole is backfilled between the hole and the pile body and compacted.

[0022] The beneficial effects of the present invention on the construction method of bored piles in karst cave areas are as follows: the present invention can effectively avoid the influence of karst cave water sources on the construction of concrete piles, and the construction is simple, efficient and can ensure the construction quality of the piles. Attached Figure Description

[0023] Figure 1 A top view of the structure during construction of this invention;

[0024] Figure 2 A front view schematic diagram of the positioning mechanism of the present invention;

[0025] Figure 3 A cross-sectional structural diagram of the present invention during construction;

[0026] Figure 4 A schematic diagram of the docking of the first card slot and the second card slot of the present invention;

[0027] 1. Soil; 2. Steel casing; 3. Cross-shaped connecting rod; 4. Positioning block; 5. Steel sleeve; 6. Guide groove; 7. Waterproof membrane segment; 7-1. First slot; 7-2. Second slot; 8. First space; 9. Second space; 10. Lifting lug; 11. Stiffening rib; 12. Hole. Detailed Implementation

[0028] The following description provides a detailed explanation of the embodiments of the present invention in a step-by-step manner. This description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limiting this invention.

[0030] Example 1

[0031] A construction method for bored piles in karst areas, such as... Figure 1-4 As shown, it includes the following steps:

[0032] Step 1: Conduct a site survey to understand the depth, size, and distribution of underground karst caves, and select suitable drilling locations accordingly; the specific survey methods are existing technologies and will not be elaborated here; selecting suitable drilling locations means: choosing locations with minimal interference from karst caves as much as possible.

[0033] Step 2: Insert the steel casing 2 into the soil at the drilling location using a drilling and pulling machine;

[0034] Step 3: Drill holes using a rotary drilling rig with a drill bit. During the drilling process, transfer the excavated soil to the ground outside the opening of the drilled hole 12 until the hole reaches the set depth.

[0035] Step 4: Clean hole 12;

[0036] Step 5: Connect the top ends of the four steel sleeves 5 through the positioning mechanism to position the four steel sleeves 5 longitudinally. Connect the positioning mechanism through the lifting equipment and hoist the four steel sleeves 5 into the hole 12.

[0037] Step 6: Guide grooves 6 are provided at both ends of the side wall of the steel sleeve 5. Waterproof plates are snapped between adjacent guide grooves 6 of adjacent steel sleeves 5. The four sets of waterproof plates form a waterproof structure for the pile body to be poured and enclose a first space 8 for pouring the pile. The function of the waterproof structure is to protect the impact of water flow or seepage in the karst cave on the pouring of the pile. A second space 9 is formed between the waterproof plate and the inner wall of the hole 12.

[0038] Step 7: Remove the positioning mechanism and pour concrete inside the steel sleeve 5; after the concrete is poured into the four steel sleeves 5, a steel-concrete composite column structure is formed to strengthen the strength of the cast-in-place pile.

[0039] Step 8: Lower the steel cage into the first space 8 and pour concrete;

[0040] Step 9: After the concrete is poured and initially formed, use a puller to pull out the steel casing 2.

[0041] Example 2

[0042] Based on Example 1, this example discloses:

[0043] like Figure 1-3 As shown, in step 5, the positioning mechanism includes four positioning blocks 4, a cross-shaped connecting rod 3, and a lifting lug 10. The four positioning blocks 4 are respectively inserted into the top end of a steel sleeve 5 and are detachably and fixedly connected to the steel sleeve 5. The free ends of the cross-shaped connecting rod 3 are bent downwards and fixedly connected to the top end of the positioning blocks 4. The lifting lug 10 is fixedly welded to the center of the top end of the cross-shaped connecting rod 3.

[0044] like Figure 1-3 As shown, in step 5, the top of the side wall of the steel sleeve 5 is provided with a connecting hole (not shown in the figure), and the outer wall of the positioning block 4 is provided with a threaded hole (not shown in the figure). The positioning block 4 and the steel sleeve 5 are fixedly connected by a bolt (not shown in the figure) that passes through the connecting hole and is screwed into the threaded hole.

[0045] Example 3

[0046] Based on Example 2, this example discloses:

[0047] like Figure 1-4 As shown, in step 6, the length of the steel sleeve 5 is consistent with the length of the pile body to be cast in, the guide groove 6 is set along the length direction of the steel sleeve 5, the top end of the guide groove 6 is flush with the top end of the steel sleeve, and the bottom end is flush with the bottom end of the steel sleeve; the four steel sleeves are evenly distributed around the axis of the pile body.

[0048] like Figure 1-4 As shown, in step 6, the waterproof membrane includes several waterproof membrane segments 7. The top and bottom ends of each waterproof membrane segment 7 are respectively provided with a first slot 7-1 and a second slot 7-2. Adjacent waterproof membrane segments 7 are engaged through the first and second slots. The left and right ends of each waterproof membrane segment 7 are respectively sealed and slidably connected to the guide grooves 6 of the corresponding steel sleeves 5. Several waterproof membrane segments 7 are sequentially stacked between adjacent guide grooves 6 of adjacent steel sleeves. The engaged waterproof membrane is coaxial with the pile body. Figure 3 , 4 As shown, during construction, waterproof membrane sections are inserted one by one between adjacent guide grooves of adjacent steel sleeves, and the first and second clamping grooves are tightened.

[0049] like Figure 1-4 As shown, in step 6, the inner surface of the guide groove 6 and the inner surface of the first slot 7-1 or the second slot 7-2 are respectively provided with elastic rubber pads. The elastic rubber pads are used to seal the left and right ends of the waterproof membrane segment with the corresponding guide grooves and to seal the first slot and the second slot that are interlocked with each other.

[0050] It should be noted that the guide groove of the present invention preferably has a T-shaped cross section, and the shape of the left and right ends of the waterproof membrane segment matches the cross-sectional shape of the guide groove. The advantage of this arrangement is that the connection between the guide groove and the end of the waterproof membrane segment will not slip due to tangential tension, and the stability of the structure can be maintained after the positioning mechanism is removed, which is beneficial to the subsequent pouring of concrete for the pile body.

[0051] Example 4

[0052] Based on Example 3, this example discloses:

[0053] The waterproof membrane is made of steel plate material. It can improve the structural strength of the cast-in-place pile by not removing it after construction, thus forming a steel pipe concrete column in the center. After construction, it can be removed and reused repeatedly.

[0054] Example 5

[0055] Based on the above embodiments, such as Figure 1-4 As shown in the figure, this embodiment discloses that step 9 further includes removing the waterproof membrane after the concrete has initially set. The outer surface of the waterproof membrane segment 7 is provided with a hanging ring (not shown in the figure) for connection with the hook. A steel wire rope is connected to a lifting device, the steel wire rope is connected to the hook, and the hook is connected to the hanging ring. The waterproof membrane segments 7 are pulled out one by one. After being pulled out, the soil excavated from the borehole is backfilled between the hole and the pile body and compacted.

[0056] Example 6

[0057] Based on the above embodiments, this embodiment discloses:

[0058] A type of bored pile in karst areas, such as Figure 1-4 As shown, the structure includes a pile body, steel-concrete composite columns, guide grooves 6, and a waterproof membrane. The steel-concrete composite columns are evenly distributed around the outer periphery of the pile body. Each steel-concrete composite column includes a steel sleeve 5 and concrete poured inside the steel sleeve 5. Guide grooves 6 are provided at both ends of the outer wall of the steel sleeve 5. A waterproof membrane is connected between adjacent steel sleeves 5. The left and right ends of the waterproof membrane are respectively sealed and slidably connected to the adjacent guide grooves 6 of the adjacent steel sleeves. The waterproof membrane is tightly connected to the outer surface of the pile body.

[0059] like Figure 1-4 As shown, the pile body includes a reinforcing cage (not shown in the figure) and concrete poured between the reinforcing cage and the inner surface of the waterproof liner and the outer surface of the steel sleeve 5.

[0060] like Figure 1-4As shown, the length of the steel sleeve 5 is the same as the length of the pile body, the guide groove 6 is set along the length direction of the steel sleeve 5, the top end of the guide groove 6 is flush with the top end of the steel sleeve 5, and the bottom end of the guide groove 6 is flush with the bottom end of the steel sleeve 5; the four steel sleeves are evenly distributed around the axis of the pile body.

[0061] like Figure 1-4 As shown, the waterproof membrane includes several waterproof membrane segments 7. The top and bottom ends of the waterproof membrane segments 7 are respectively provided with a first slot 7-1 and a second slot 7-2. The upper and lower adjacent waterproof membrane segments are snapped together by the first slot and the second slot. The left and right ends of the waterproof membrane segments are respectively sealed and slidably connected to the guide grooves 6 of the corresponding steel sleeves 5. Several waterproof membrane segments 7 are stacked sequentially between the adjacent guide grooves 6 of the adjacent steel sleeves 5. The snapped waterproof membrane is coaxial with the pile body.

[0062] like Figure 1-4 As shown, the inner surface of the guide groove 6 and the inner surface of the first slot 7-1 or the second slot 7-2 are respectively provided with elastic rubber pads (not shown in the figure).

[0063] like Figure 1-4 As shown, it also includes a positioning mechanism, which includes four positioning blocks 4, a cross-shaped connecting rod 3, and a lifting lug 10. The four positioning blocks 4 are respectively inserted into the top end of a steel sleeve 5 and are detachably and fixedly connected to the steel sleeve 5. The free ends of the cross-shaped connecting rod 3 are respectively bent downward and fixedly connected to the top end of the positioning blocks 4. The lifting lug 10 is fixedly welded to the center of the top end of the cross-shaped connecting rod 3.

[0064] like Figure 1-4 As shown, the top of the side wall of the steel sleeve 5 is provided with a connecting hole, and the outer wall of the positioning block 4 is provided with a threaded hole. The positioning block 4 and the steel sleeve 5 are fixedly connected by a bolt (not shown in the figure) that passes through the connecting hole and is screwed into the threaded hole.

Claims

1. A construction method for bored piles in karst areas, characterized in that, Includes the following steps: Step 1: Conduct a site survey to understand the depth, size, and distribution of underground karst caves, and select suitable drilling locations accordingly; Step 2: Insert the steel casing into the soil at the drilling location using a drilling and pulling machine; Step 3: Drill holes using a rotary drilling rig with a drill bit. During the drilling process, the excavated soil is transferred to the ground outside the hole opening until the set depth is reached. Step 4: Clean the holes; Step 5: Connect the top ends of the four steel sleeves through the positioning mechanism to position the four steel sleeves longitudinally. Connect the positioning mechanism through the lifting equipment and hoist the four steel sleeves into the hole. Step 6: Guide grooves are provided at both ends of the side wall of the steel sleeve. Waterproof plates are snapped between the adjacent guide grooves of adjacent steel sleeves. The four sets of waterproof plates form a waterproof structure for the pile body to be poured and enclose a first space for pouring the pile. A second space is formed between the waterproof plate and the inner wall of the hole. Step 7: Remove the positioning mechanism and pour concrete inside the steel casing; after pouring concrete into the four steel casings, a steel-concrete composite column structure is formed to strengthen the strength of the cast-in-place pile. Step 8: Lower the steel cage into the first space and pour concrete; Step 9: After the concrete is poured and initially formed, the steel casing is pulled out using a puller. The waterproof membrane is removed after the concrete in the pile body has initially set. After the waterproof membrane is pulled out, the soil excavated from the borehole is backfilled between the hole and the pile body and compacted.

2. The construction method for bored piles in karst areas as described in claim 1, characterized in that, In step 5, the positioning mechanism includes four positioning blocks, a cross-shaped connecting rod, and a lifting lug. The four positioning blocks are respectively inserted into the top of a steel sleeve and are detachably and fixedly connected to the steel sleeve. The free ends of the cross-shaped connecting rod are bent downwards and fixedly connected to the top of the positioning blocks. The lifting lug is fixedly welded to the center of the top of the cross-shaped connecting rod.

3. The construction method for bored piles in karst areas as described in claim 2, characterized in that, In step 5, the top of the side wall of the steel sleeve is provided with a connecting hole, and the outer wall of the positioning block is provided with a threaded hole. The positioning block and the steel sleeve are fixedly connected by bolts that pass through the connecting hole and are screwed into the threaded hole.

4. The construction method for bored piles in karst areas as described in claim 3, characterized in that, In step 6, the length of the steel sleeve is the same as the length of the pile body to be cast in. The guide groove is set along the length of the steel sleeve, with the top end of the guide groove flush with the top end of the steel sleeve and the bottom end flush with the bottom end of the steel sleeve. The four steel sleeves are evenly distributed around the axis of the pile body.

5. The construction method for bored piles in karst areas as described in claim 4, characterized in that, In step 6, the waterproof membrane includes several waterproof membrane segments. The top and bottom ends of each waterproof membrane segment are provided with a first slot and a second slot, respectively. Adjacent waterproof membrane segments are snapped together through the first slot and the second slot. The left and right ends of each waterproof membrane segment are respectively sealed and slidably connected to the guide grooves of the corresponding steel sleeves. Several waterproof membrane segments are stacked sequentially between the adjacent guide grooves of adjacent steel sleeves. The snapped waterproof membrane is coaxial with the pile body.

6. The construction method for bored piles in karst areas as described in claim 5, characterized in that, In step 6, the inner surface of the guide groove and the inner surface of the first or second slot are respectively provided with elastic rubber pads. The elastic rubber pads are used to seal the left and right ends of the waterproof membrane segment with the corresponding guide grooves and to seal the first and second slots that are interlocked with each other.

7. The construction method for bored piles in karst areas as described in claim 6, characterized in that, Step 9 further includes providing hanging rings on the outer surface of the waterproof membrane segments for connection with hooks, connecting steel wire ropes via lifting equipment, connecting the steel wire ropes to hooks, moving the hooks downwards along the second space and connecting to the hanging rings, thus pulling out the waterproof membrane segments one by one.

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