Drilling method for hard inclined rock surface cast-in-place pile

Abstract

The invention provides a hard inclined rock surface cast-in-place pile drilling method, and relates to the technical field of constructional engineering. The hard inclined rock surface cast-in-place pile drilling method comprises the steps that the soft rock stratum position of a pile hole is determined; a first excess steel bar of a pile foundation reinforcement cage main bar is inserted into the soft rock stratum in the axial direction of a pile hole, and a first layer of rubble is backfilled; a percussion drill is used for pressing the first excess steel bars and the first layer of rubbles into the soft rock stratum; second excess material reinforcing steel bars of main reinforcements of the pile foundation reinforcing cage are made into reinforcing steel bar meshes, and the reinforcing steel bar meshes are horizontally filled into the pile holes; backfilling a second layer of rubble on the reinforcing mesh; impacting the second layer of rubbles by using the percussion drill; and drilling. And through combined backfilling of the horizontal reinforcing mesh and the second layer of rubbles, the uniformity of an impact interface can be improved, and deflection of a drilling tool of the impact drill is avoided, so that the drilling construction efficiency can be improved while the drilling cost of the hard inclined rock surface cast-in-place pile can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, and in particular to a method for drilling cast-in-place piles on a hard inclined rock surface. Background Art

[0002] In the hard inclined rock surface, bored piles in the inclined rock area can be divided into soft rock layers with smaller bearing capacity and hard rock layers with larger bearing capacity due to the different bearing capacity of the geology on both sides of the hole bottom. Accidents such as inclined piles, hole expansion, buried drills, and even broken piles are easy to occur during drilling.

[0003] At present, the main method for drilling pile foundations on inclined rock surfaces is to backfill high-strength slabs, pour early-strength concrete or use underwater blasting before drilling holes. Conventional high-strength slabs or pouring early-strength concrete treatments have a long construction period and low efficiency, and the procurement cost of high-strength slabs is relatively high, especially in areas such as karst areas where high-strength slabs are scarce. The procurement of high-strength slabs will significantly increase the construction cost. Summary of the invention

[0004] The problem solved by the invention is: how to achieve a balance between construction cost and drilling construction efficiency on an inclined hard rock surface.

[0005] In order to solve the above problems, the present invention provides a method for drilling cast-in-place piles on a hard inclined rock surface, comprising:

[0006] Determine the location of the weak rock formation for the pile hole;

[0007] Inserting the first remaining steel bars of the main reinforcement of the pile foundation steel cage into the soft rock layer along the axial direction of the pile hole, and backfilling the first layer of stone;

[0008] Using an impact drill to press the first remaining steel bars and the first layer of stone into the soft rock layer;

[0009] The second surplus steel bars of the main reinforcement of the pile foundation steel cage are made into a steel mesh, and the steel mesh is horizontally filled into the pile hole;

[0010] Backfilling a second layer of stone on the steel mesh;

[0011] Using the impact drill to impact the second layer of slab stones;

[0012] drilling.

[0013] Optionally, the thickness of the first layer of flakes is KDtanθ / 2, wherein D is the pile hole diameter, θ is the angle of the inclined rock surface, and K is the density of the soft rock layer.

[0014] Optionally, the method for drilling cast-in-place piles on a hard inclined rock surface further comprises periodically detecting the hole depth during the impact drilling process, and stopping the impact when the difference between the hole bottom elevation and the highest point elevation of the inclined rock surface is in the range of 0.3 to 0.5 m.

[0015] Optionally, the method for boring cast-in-place piles on a hard inclined rock surface further comprises: during the impact drilling process of the impact drill, the mud specific gravity takes a value range of 1.2 to 1.4.

[0016] Optionally, the distance d between two adjacent steel bars of the steel mesh is in the range of 0.15 to 0.3 m, and the diameter of the steel mesh is 10 cm smaller than the diameter of the pile hole.

[0017] Optionally, the method for boring cast-in-place piles on a hard inclined rock surface also includes providing one layer of the steel mesh on the side close to the hard rock layer, and providing multiple layers of the steel mesh on the side close to the soft rock layer.

[0018] Optionally, the thickness of the second layer of slabs is in the range of 0.3-0.5 m, and the diameter of the slabs is in the range of 0.5-0.8 m.

[0019] Optionally, the method for drilling cast-in-place piles on a hard inclined rock surface further includes: in step three, when the impact drill impacts the second layer of flaky stones, the stroke range of the impact drill is 0.5 to 1 m.

[0020] Optionally, the hard inclined rock surface cast-in-place pile drilling method further comprises:

[0021] If the drilled slag contains steel bar slag, stop impacting;

[0022] The number of layers of the steel mesh is increased, and the second layer of stone is backfilled before impact drilling.

[0023] Optionally, the method for drilling cast-in-place piles on a hard inclined rock surface further includes stopping the drilling when the pile foundation drilling reaches the inclined hard rock surface and the steel wire rope of the impact drill swings or an abnormal noise occurs during the punching process.

[0024] Compared with the related art, the method for boring cast-in-place piles on hard inclined rock surface of the present invention can use an impact drill to press the first surplus steel bar and the first layer of stone into the weak rock layer during the boring construction of the cast-in-place piles on hard inclined rock surface and after determining the position of the weak rock layer of the pile hole, so that the structural strength of the first surplus steel bar is used to improve the structural strength of the weak rock layer together with the first layer of stone, and the combined backfilling of the first surplus steel bar and the first layer of stone can save the construction time of pouring early-strength concrete, thereby reducing the drilling time, and the first surplus steel bar is used as the surplus of the main reinforcement of the pile foundation reinforcement cage, so the material is simple, and the surplus of the main reinforcement of the pile foundation reinforcement cage can be reused, reducing the first surplus steel bar The cost of use can be improved to a certain extent, so as to avoid purchasing high-strength stone flakes, thereby reducing the purchase cost of high-strength stone flakes and further reducing the cost of bored pile drilling on hard inclined rock surfaces. Then, a steel mesh is made from the second surplus steel bars of the main reinforcement of the pile foundation reinforcement cage, and the steel mesh is horizontally filled into the pile hole. The second layer of stone flakes is backfilled on the steel mesh, and the impact drill impacts the second layer of stone flakes, thereby further realizing the secondary utilization of the surplus materials of the main reinforcement of the pile foundation reinforcement cage. At the same time, the combined backfill of the horizontal steel mesh and the second layer of stone flakes can improve the uniformity of the impact interface and avoid the deviation of the drill tool of the impact drill, thereby reducing the cost of bored pile drilling on hard inclined rock surfaces and improving the drilling construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flowchart of a method for boring cast-in-place piles on a hard inclined rock surface in an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of the distribution of hard rock layers and soft rock layers in the pile hole in the embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of backfilling the first layer of rubble in an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram when the elevation of the bottom of the hole is 0.3-0.5m from the elevation of the highest point of the hard rock formation in the embodiment of the present invention;

[0029] Figure 5 is a layout diagram of a steel mesh in an embodiment of the present invention;

[0030] Figure 6 It is a layout diagram of impact drilling after backfilling the steel mesh in an embodiment of the present invention;

[0031] Figure 7 Schematic diagram of the drilling process in the embodiment of the present invention Figure 1 ;

[0032] Figure 8 Schematic diagram of the drilling process in the embodiment of the present invention Figure 2 ;

[0033] Fig. 9 Schematic diagram of the drilling process in the embodiment of the present invention Figure 2 .

[0034] Description of reference numerals:

[0035] 1-pile hole; 2-hard rock layer; 3-soft rock layer; 4-rock surface boundary line; 5-first surplus steel bar; 6-steel mesh; 7-first layer of stone; 8-second layer of stone. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] In the drawings, the X-axis represents the horizontal position, and the positive direction of the X-axis (that is, the direction in which the arrow of the X-axis points) represents the right side, and the negative direction of the X-axis (that is, the direction opposite to the positive direction of the X-axis) represents the left side; in the drawings, the Z-axis represents the vertical position, and the positive direction of the Z-axis (that is, the direction in which the arrow of the Z-axis points) represents the upper side, and the negative direction of the Z-axis (that is, the direction opposite to the positive direction of the Z-axis) represents the lower side. It should also be noted that the aforementioned Z-axis and X-axis are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0039] In the hard inclined rock surface, bored piles in the inclined rock area can be divided into soft rock layers with smaller bearing capacity and hard rock layers with larger bearing capacity due to the different bearing capacity of the geology on both sides of the hole bottom. Accidents such as inclined piles, hole expansion, buried drills, and even broken piles are easy to occur during drilling.

[0040] At present, the main method for drilling pile foundations on inclined rock surfaces is to backfill high-strength stone, pour early-strength concrete or use underwater blasting methods before performing impact drilling. Conventional high-strength stone or pouring early-strength concrete methods have a long construction period and low efficiency, and the procurement cost of high-strength stone is relatively high, especially in areas such as karst areas where high-strength stone is scarce. The procurement of high-strength stone will significantly increase the construction cost. Underwater blasting has high safety risks. The use of down-the-hole drilling + impact drilling requires the addition of down-the-hole drilling equipment and steel casing. For projects where only a few pile foundations are located on inclined hard rock surfaces, the cost is high and the process is relatively complicated. Based on the above problems, an embodiment of the present invention proposes a method for drilling bored piles on hard inclined rock surfaces, which is suitable for areas such as karst areas that lack high-strength flaky stones. The method utilizes the remaining steel bars from the pile foundation steel cage to make a steel mesh, and the steel bars, steel mesh and flaky stones are backfilled into the pile hole, thereby ensuring the uniformity of the force on the impact interface. The method can quickly solve the problem of pile foundation drilling deviation on inclined rock surfaces and improve the efficiency of drilling construction on inclined rock surfaces.

[0041] Combination Figures 1 to 9 As shown, the present invention provides a method for drilling cast-in-place piles on a hard inclined rock surface, comprising:

[0042] Step 1: determine the location of the weak rock layer 3 of the pile hole 1;

[0043] Step 2: insert the first surplus steel bar 5 of the main reinforcement of the pile foundation steel cage into the soft rock layer 3 along the axial direction of the pile hole 1, and backfill the first layer of stone 7;

[0044] Step 3: Use an impact drill to press the first excess steel bars 5 and the first layer of stone 7 into the soft rock layer 3;

[0045] Step 4: Make the second surplus steel bars of the main reinforcement of the pile foundation steel cage into a steel mesh 6, and fill the steel mesh 6 horizontally into the pile hole 1;

[0046] Step 5: backfill the second layer of stone 8 on the steel mesh 6;

[0047] Step 6: Use an impact drill to impact the second layer of stone 8;

[0048] Step 7: Drilling.

[0049] Specifically, in the pile hole 1, the position where the hard rock layer 2 and the weak rock layer 3 contact is the rock surface boundary line 4, such as Figure 2 As shown in FIG. 4 , the soft rock layer 3 is located above the rock surface boundary line 4, and the hard rock layer 2 is located below the rock surface boundary line 4. Figure 2As shown in the figure, when it is found that the borehole has been drilled to the inclined hard rock surface and it is determined that the weak rock layer 3 is located on the upper left of the hard rock layer 2, the drill is withdrawn from the pile hole 1, and the remaining part of the steel bars after the main reinforcement of the pile foundation reinforcement cage is made at the construction site is the first surplus steel bar 5, and the remaining part is the second surplus steel bar. Figure 3 As shown, the first excess steel bar 5 is inserted into the soft rock layer 3 along the axial direction of the pile hole 1, and the first layer of stone 7 is backfilled on the first expected steel bar. After the first layer of stone 7 is backfilled, the first layer of stone 7 is impacted by the impact drill. During the impact drill impacting the first layer of stone 7, the first layer of stone 7 can be pressed into the soft rock layer 3, and the first expected steel bar can also be pressed into the soft rock layer 3, as shown in FIG. Figure 4 As shown, the first surplus steel bars 5 and the first layer of stone 7 are evenly distributed in the soft rock layer 3, and the rigidity of the first surplus steel bars 5 and the first layer of stone 7 is used to improve the structural strength of the soft rock layer 3, as shown in FIG. Figure 5 and Figure 6 At the construction site, the second surplus steel bar is used to make a steel mesh 6, and the steel mesh 6 is horizontally filled into the pile hole 1. Then, the second layer of stone 8 is backfilled on the horizontal steel mesh 6. Under the support of the horizontal steel mesh 6, the impact drill impacts the second layer of stone 8 so that the plane filled by the second layer of stone 8 in the pile hole 1 is also a horizontal plane. Figures 7 to 9 As shown, drilling is performed until the inclined hard rock layer 2 is constructed into a horizontal state. During the drilling process, the bearing capacity of the weak rock layer 3 is improved by the first expected steel bars and the first layer of stone 7, and the horizontal steel mesh 6 makes the second layer of stone 8 more evenly stressed, avoiding the tilting of the drilling tool of the impact drill due to the filling of the second layer of stone 8, thereby not only improving the structural strength of the weak rock layer 3, but also solving the problem of the deflection of the pile foundation drilling on the inclined rock surface, so as to improve the efficiency of the bored pile drilling on the hard inclined rock surface. In addition, this embodiment utilizes the remaining material after the main reinforcement of the pile foundation steel cage is made at the construction site, which can reduce the amount of high-strength stone, and does not need to pour early-strength concrete or perform underwater blasting. Therefore, it can reduce the cost of bored pile holes on hard inclined rock surfaces.

[0050] Therefore, in this embodiment, during the construction of bored piles on a hard inclined rock surface, and after determining the position of the soft rock layer 3 of the pile hole 1, the first surplus steel bar 5 and the first layer of stone 7 can be pressed into the soft rock layer 3 by using an impact drill, so that the structural strength of the first surplus steel bar 5 can be used together with the first layer of stone 7 to improve the structural strength of the soft rock layer 3, and the combined backfilling of the first surplus steel bar 5 and the first layer of stone 7 can save the construction time of pouring early-strength concrete, thereby reducing the drilling time, and the first surplus steel bar 5 is used as the surplus of the main reinforcement of the pile foundation reinforcement cage, which is simple to obtain, and the surplus of the main reinforcement of the pile foundation reinforcement cage can be reused, thereby reducing the use cost of the first surplus steel bar 5. To a certain extent, the purchase of high-strength stone can be avoided to reduce the purchase cost of high-strength stone, and the cost of drilling bored piles on hard inclined rock surfaces can be further reduced. Then, the second surplus steel bars of the main reinforcement of the pile foundation reinforcement cage are used to make a steel mesh 6, and the steel mesh 6 is horizontally filled into the pile hole 1, and the second layer of stone 8 is backfilled on the steel mesh 6. The impact drill impacts the second layer of stone 8, and further realizes the secondary utilization of the surplus of the main reinforcement of the pile foundation reinforcement cage. At the same time, the combined backfill of the horizontal steel mesh 6 and the second layer of stone 8 can improve the uniformity of the impact interface and avoid the deviation of the drill tool of the impact drill, thereby reducing the cost of drilling bored piles on hard inclined rock surfaces while improving the drilling construction efficiency.

[0051] Optionally, combined Figure 5 As shown, the thickness of the first layer of stone 7 is KDtanθ / 2, where D is the diameter of the pile hole 1, θ is the angle of the inclined rock surface, and K is the density of the soft rock layer 3. θ and K can be obtained according to the geological survey report.

[0052] Specifically, K is the density of the soft rock layer 3, and the value range is generally between 1 and 2. When drilling, the thickness of the first layer of backfilled stone can be 1.2×2×tan45° / 2=1.2m, wherein the block diameter of the first layer of backfilled stone is between 0.8-1.2m. Considering that the first layer of stone 7 needs to be pressed into the soft rock layer 3, if the thickness of the first layer of stone 7 pressed into the soft rock layer 3 is too thick, the material of the first layer of stone 7 will be too much, and the cost will be high. If the thickness of the first layer of stone 7 pressed into the soft rock layer 3 is too thin, the first layer of stone 7 will not be able to play a role in improving the bearing strength of the soft rock layer 3 with the first surplus steel bar 5. Among them, in the process of backfilling the first layer of backfill stone, the block diameter of the first layer of backfill stone is relatively large, and the block diameter of the subsequent backfill stone is relatively small, which further reduces the use cost of the stone. In addition, after the first backfilling, the stroke of the drill bit of the impact drill is also relatively large, so as to utilize the stone with a larger block diameter to insert the first surplus steel bar 5 into the weak rock layer 3.

[0053] In this way, the thickness of the first layer of stone 7 is KDtanθ / 2, wherein D is the diameter of the pile hole 1, θ is the angle of the inclined rock surface, and K is the density of the soft rock layer 3. The thickness of the first layer of stone 7 can be calculated so that the thickness of the first layer of stone 7 is moderate to ensure that after the first layer of stone 7 is filled, the impact of the impact drill can completely press the backfilled first layer of stone 7 into the soft rock layer 3, thereby ensuring that the first layer of stone 7 can effectively improve the bearing capacity of the soft rock layer 3.

[0054] Alternatively, if Figure 4 As shown, the method for drilling cast-in-place piles on a hard inclined rock surface also includes: in step three, during the impact drilling process, the hole depth is regularly checked, and when the difference between the hole bottom elevation and the elevation of the highest point of the inclined rock surface is in the range of 0.3 to 0.5 m, the impact is stopped.

[0055] Specifically, the hole bottom elevation refers to the vertical distance between the hole bottom or the first layer of stone 7 and the top of the pile hole 1. The elevation of the highest point of the inclined rock surface refers to the vertical distance between the highest position of the inclined hard rock surface and the top of the pile hole 1. When the difference between the hole bottom elevation and the highest point of the inclined rock surface is in the range of 0.3 to 0.5 m, the impact is stopped.

[0056] In this way, during the impact drilling process, the hole depth is regularly checked, and the impact is stopped when the difference between the hole bottom elevation and the highest point of the inclined rock surface is in the range of 0.3 to 0.5 m. At this time, the hole bottom is 0.3 to 0.5 m away from the highest point of the inclined rock surface, which can avoid the impact drill from repeatedly impacting the hard inclined rock surface, causing an inclined hole or a hole expansion and buried drill, so as to improve the efficiency of the drilling construction. At the same time, the difference between the hole bottom elevation and the highest point of the inclined rock surface is in the range of 0.3 to 0.5 m, which can avoid the backfill thickness of the first layer of stone 7 being too thick, the impact drill punching time being long, and affecting the drilling efficiency. At the same time, it can also avoid the backfill thickness of the first layer of stone 7 being too thin, and the number of backfills of the first layer of stone 7 is reduced, so as to improve the construction efficiency.

[0057] Optionally, the method for boring cast-in-place piles on a hard inclined rock surface further includes: during the impact drilling process, the mud specific gravity is in the range of 1.2 to 1.4.

[0058] Specifically, during the drilling process of the impact drill, the mud can maintain the stability of the pile hole. If the mud specific gravity is less than 1.2 during the drilling process, the mud skin formed during the drilling process is too thin, the hole strength is low, and the drilling efficiency is affected. If the mud specific gravity is greater than 1.4 during the drilling process, the mud skin formed during the drilling process is too thick, which increases the load of the drill and affects the drilling efficiency.

[0059] In this way, during the impact of the impact drill, the mud density ranges from 1.2 to 1.4, which ensures the stability of the hole wall during the drilling process and ensures that the mud skin formed during the drilling process is not too thick or too thin, so as to improve the drilling efficiency.

[0060] Optionally, combined Figure 5 As shown, the distance d between two adjacent steel bars of the steel mesh 6 ranges from 0.15 to 0.3 m, and the diameter of the steel mesh 6 is 10 cm smaller than the diameter of the pile hole 1 .

[0061] Thus, the spacing d between two adjacent steel bars of the steel mesh 6 is in the range of 0.15 to 0.3 m, making the structure of the steel mesh 6 relatively compact, and ensuring that the structure of the steel mesh 6 is more secure. The size of the steel mesh 6 is 10 cm smaller than the diameter of the pile hole 1, which can prevent the end of the steel bar from colliding with the mud skin on the hole wall during the process of lowering the steel mesh 6 into the pile hole 1, causing leakage.

[0062] In some embodiments, the thickness of the backfill of the steel mesh 6 is in the range of 0.3 to 0.5 m, which can avoid repeated impacts on the hard inclined rock surface to cause inclined holes or expanded holes and buried drills, so as to ensure the quality of the drilling and thereby improve the efficiency of the drilling construction.

[0063] Alternatively, if Figure 5 As shown, the method for boring cast-in-place piles on a hard inclined rock surface also includes providing one layer of steel mesh 6 on the side close to the hard rock layer 2 and providing multiple layers of steel mesh 6 on the side close to the soft rock layer 3.

[0064] Specifically, Figure 5 a represents the side close to the soft rock layer 3, and b represents the side close to the hard rock layer 2. Only one layer of steel mesh 6 is arranged on the hard rock layer 2 side, and two layers of steel mesh 6 are arranged on the soft rock layer 3 side, in order to balance the strength of the hard rock layer 2 side and the strength of the soft layer side, and fully ensure the uniformity of the bearing capacity of the impact interface.

[0065] In this way, the number of layers of the steel mesh 6 on the side close to the hard rock layer 2 is one, while the number of layers of the steel mesh 6 on the side close to the soft rock layer 3 is multiple, which fully ensures the uniformity of the bearing capacity of the impact interface.

[0066] Optionally, the thickness of the second layer of stones 8 may range from 0.3 to 0.5 m, and the diameter of the stones may range from 0.5 to 0.8 m.

[0067] In this way, the thickness of the second layer of stone 8 is in the range of 0.3-0.5m, which can avoid the backfill thickness of the second layer of stone 8 being too thick, which will take a long time for the impact drill to punch holes and affect the drilling efficiency. At the same time, it can also avoid the backfill thickness of the second layer of stone 8 being too thin and unable to fully utilize the strength of the steel bars, reducing the number of backfill times of the second layer of stone 8 to improve construction efficiency. The diameter of the stone block is in the range of 0.5-0.8m, which can reduce the procurement cost of the stone.

[0068] Optionally, the method for drilling cast-in-place piles on a hard inclined rock surface further includes the step of impact drilling impacting the second layer of stone 8, wherein the stroke of the impact drill is in the range of 0.5 to 1 m.

[0069] Specifically, the stroke of an impact drill refers to the distance the drill bit moves back and forth in the drill rod when the impact drill is working.

[0070] Thus, when the second layer of stone 8 is impacted by the impact drill, the stroke of the impact drill is in the range of 0.5 to 1 m, so that the impact drill stroke is relatively small to avoid bending of the steel mesh 6 due to excessive impact force.

[0071] Optionally, the hard inclined rock surface cast-in-place pile drilling method further comprises:

[0072] If the drilled slag contains steel bar 6 slag, stop impacting;

[0073] The number of layers of the steel mesh 6 is increased, and the impact drilling is performed after the second layer of stone 8 is backfilled.

[0074] Specifically, during the drilling process, slag analysis is performed to determine whether the slag contains steel mesh 6 slag. If so, it means that the steel bars 6 are broken by the impact hammer of the impact drill during the impact process, which may easily cause the deviation of the subsequent drilling. Therefore, when steel bar 6 slag appears, the impact drill is stopped, and the number of layers of steel mesh 6 is increased, and the second layer of stone 8 is backfilled before impact drilling to ensure the quality of subsequent drilling.

[0075] In this way, if the slag sample of the drilling hole contains hard rock or steel slag sample, the impact is stopped; increasing the number of layers of the steel mesh 6 and backfilling the second layer of stone 8 before impact drilling can ensure the quality of the drilling and improve the drilling efficiency.

[0076] Optionally, the method for drilling cast-in-place piles on a hard inclined rock surface further includes stopping the drilling when the pile foundation drilling reaches the inclined hard rock surface and the steel wire rope of the impact drill swings or an abnormal noise occurs during the punching process.

[0077] Specifically, when the impact hammer of the impact drill approaches the inclined hard rock layer 2 for drilling, due to the different strengths of the soft rock layer 3 and the hard rock layer 2, the impact hammer slides down slightly along the rock surface boundary line 4, causing the wire rope to swing, or the impact hammer is obstructed by the hard rock layer 2, causing a collision and abnormal noise. In either case, drilling needs to be stopped to avoid subsequent continuous drilling resulting in an inclined hole. At the same time, the impact hammer can be protected from being overloaded.

[0078] In this way, when the pile foundation drilling reaches the inclined hard rock surface and the wire rope of the impact drill swings or an abnormal noise occurs during the punching process, the drilling is stopped, and the working condition of the impact hammer drilling is judged timely and effectively, avoiding damage to the impact hammer that prolongs the drilling construction time, thereby improving the drilling efficiency.

[0079] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for drilling cast-in-place piles on a hard inclined rock surface, characterized in that ,include: Determine the location of the weak rock formation for the pile hole; Inserting the first remaining steel bars of the main reinforcement of the pile foundation steel cage into the soft rock layer along the axial direction of the pile hole, and backfilling the first layer of stone; Using an impact drill to press the first remaining steel bars and the first layer of stone into the soft rock layer; The second surplus steel bars of the main reinforcement of the pile foundation steel cage are made into a steel mesh, and the steel mesh is horizontally filled into the pile hole; Backfilling a second layer of stone on the steel mesh; Using the impact drill to impact the second layer of slab stones; drilling.

2. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: The thickness of the first layer of stone is KDtanθ / 2, where D is the pile hole diameter, θ is the angle of the inclined rock surface, and K is the density of the soft rock layer.

3. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: The method also includes periodically detecting the hole depth during the impact drilling process, and stopping the impact when the difference between the hole bottom elevation and the highest point elevation of the inclined rock surface is in the range of 0.3 to 0.5 m.

4. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: Also includes: During the percussion drilling process, the mud specific gravity ranges from 1.2 to 1.

4.

5. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: The distance d between two adjacent steel bars of the steel mesh is in the range of 0.15 to 0.3 m, and the diameter of the steel mesh is 10 cm smaller than the diameter of the pile hole.

6. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: It also includes that the number of layers of the steel mesh on the side close to the hard rock layer is one layer, and the number of layers of the steel mesh on the side close to the soft rock layer is multiple layers.

7. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: The thickness of the second layer of slabs is in the range of 0.3-0.5 m, and the diameter of the slabs is in the range of 0.5-0.8 m.

8. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: It also includes: in step three, when the impact drill impacts the second layer of stone, the stroke range of the impact drill is 0.5 to 1 m.

9. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: Also includes: If the drilled slag contains steel bar slag, stop impacting; The number of layers of the steel mesh is increased, and the second layer of stone is backfilled before impact drilling.

10. The method for drilling cast-in-place piles on hard inclined rock surface according to claim 1, characterized in that: The method also includes stopping the drilling when the pile foundation drilling reaches an inclined hard rock surface and the steel wire rope of the impact drill swings or an abnormal sound occurs during the punching process.

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