A drilling high-pressure grouting integrated device

Abstract

This invention discloses an integrated drilling and high-pressure grouting device, comprising: a drill rod, a drill bit, a drilling rig, a mud removal device, and a grouting device. The drill rod contains a grouting pipe, and a spiral conveyor belt is welded to the outer wall of the grouting pipe. The outer side of the spiral conveyor belt is welded to the inner wall of the drill rod. The drill rod and the drill bit are connected by a thread, and a detachable connection device is provided at the end of the drill rod away from the drill bit. During drilling, the spiral conveyor belt is connected to the mud removal device via the detachable connection device; during grouting, the grouting pipe is connected to the grouting device via the detachable connection device. This device integrates both a conveyor belt and a grouting pipe within the drill rod, achieving dual functionality in one rod. This reduces the number of equipment and construction procedures, improves construction efficiency, and eliminates the need for separate drilling and grouting equipment, saving space on the construction site.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of civil engineering, in particular to a drilling and high-pressure grouting integrated device. BACKGROUND

[0002] High-pressure grouting technology is a technology that injects slurry into the stratum through a high-pressure pump, where the slurry is a bacterial solution or microorganisms, thereby improving the properties of the stratum or achieving other engineering purposes, and is widely used in the fields of foundation reinforcement, seepage prevention and leakage plugging, slope treatment, etc. In actual engineering, drilling and grouting are two key steps. Drilling technology mainly includes percussion drilling, rotary drilling, spiral drilling, etc., which are mainly applied in the fields of geological exploration, mineral exploitation, etc. Grouting technology includes static pressure grouting, high-pressure jet grouting, composite grouting, etc., and is mainly used in foundation reinforcement, seepage prevention and leakage plugging, etc. However, the traditional high-pressure grouting technology usually needs to operate the drilling and grouting equipment separately, which is tedious and inefficient, and requires a large space. And because of the separation of equipment, it needs to move and install the equipment twice, resulting in increased cost and prolonged construction period.

[0003] In order to solve the above problems, some devices and methods are proposed in the prior art. For example, a microbial temperature control grouting gas production anti-liquefaction integrated vibration table experimental device with announcement number CN116731819A, by integrating microbial culture and grouting, the process of disassembling the sample box and the vibration table test sample is omitted, the electromagnetic vibration table can realize accurate control of the amplitude and frequency of the sample box, the structure is relatively simple, and the installation is also relatively convenient. Announcement number CN117966749A discloses a drilling double-cylinder grouting integrated machine for enhancing the mixing of liquid, which mixes the liquid multiple times and in multiple ways through static mixing pipes, semi-dynamic mixing pipes and dynamic mixing pipes, so that the liquid is stripped, divided, cross-mixed, fused and pierced, etc., realizing the enhanced mixing of the liquid and ensuring the grouting quality. Announcement number CN117927155A discloses a microbial grouting drilling integrated machine for reinforcing sand and a grouting method, which realizes the injection of two different slurries into the drilling rod without contact through a double-liquid drilling rod and a double-liquid grouting pump, so as to prevent the mutual reaction of the two solutions and cause the blockage of the drilling rod.

[0004] Although the prior art has solved the problem of separate operation of drilling and grouting to some extent, there are still some deficiencies. First, some devices integrate multiple modules, resulting in complex device structure, difficult installation and maintenance, and not conducive to rapid deployment and use on the construction site. Second, some devices are large in size and heavy in weight, which may not be very convenient to move, which may limit the use range of the device, especially in some narrow space, it is difficult to meet the demand of flexible construction. In addition, the complex structure of the device also increases the difficulty of operation, which may affect the precision and efficiency of operation and increase the labor intensity of construction personnel. These problems to some extent limit the application and development of existing high-pressure grouting technology, which needs to be further optimized and improved. SUMMARY

[0005] The present application provides a drilling and high-pressure grouting integrated device, which solves the problem of low grouting efficiency and device utilization rate of existing high-pressure grouting technology.

[0006] To solve the above technical problems, the present application provides a drilling and high-pressure grouting integrated device, which comprises a drill pipe, a drill bit, a drilling machine, a mud discharge device and a grouting device. The drill pipe is internally provided with a grouting pipeline, the outer wall of the grouting pipeline is welded with a spiral conveyor belt, the outer side of the spiral conveyor belt is welded with the inner wall of the drill pipe, the drill pipe and the drill bit are connected through threads, and the end of the drill pipe away from the drill bit is provided with a detachable connecting device. When the device drills, the spiral conveyor belt is connected with the mud discharge device through the detachable connecting device; when the device grouts, the grouting pipeline is connected with the grouting device through the detachable connecting device.

[0007] Preferably, the drill bit comprises a plurality of blades, the blades are arranged in a spiral around the central axis of the drill bit, and a certain distance is maintained between adjacent blades.

[0008] Preferably, the mud discharge device comprises a first buffer pool, a second buffer pool, a sand and stone pump, a first motor and a second motor. The bottom of the first buffer pool is connected with the drill pipe through a detachable connecting device, the first buffer pool, the second buffer pool and the sand and stone pump are connected through pipelines, the second buffer pool is connected with the first motor, and the sand and stone pump is connected with the second motor.

[0009] Preferably, the top of the first buffer pool is provided with a spraying device.

[0010] Preferably, a first filter screen is arranged between the second buffer pool and the first motor.

[0011] Preferably, the grouting device comprises a cup barrel, a high-pressure pump, a third buffer pool, and a fourth buffer pool, the bottom of the third buffer pool is connected with the drill rod through detachable connecting device, the third buffer pool, the fourth buffer pool and the cup barrel are connected through pipelines, and the high-pressure pump is arranged between the fourth buffer pool and the cup barrel.

[0012] Preferably, a first pressure gauge is arranged between the third buffer pool and the fourth buffer pool, a second pressure gauge is arranged between the fourth buffer pool and the cup barrel, a gearbox is arranged on the pipeline between the fourth buffer pool and the cup barrel, and the high-pressure pump is connected with the gearbox.

[0013] Preferably, a second filter screen is arranged between the cup barrel and the fourth buffer pool.

[0014] Preferably, the bottom of the fourth buffer pool is provided with a roller.

[0015] Preferably, a casing is arranged around the drill rod close to the ground.

[0016] The present application has at least the following advantages:

[0017] 1. The drill rod is provided with a conveyor belt and a grouting pipeline inside, the drilling and grouting functions are integrated on the same drill rod, one rod is used for two purposes, the number of equipment and the conversion of construction procedures are reduced, and the construction efficiency is improved.

[0018] 2. The drill rod is threadedly connected with the drill bit, the drill bit can be conveniently installed, disassembled and replaced, appropriate drill bits can be selected according to different stratum conditions, meanwhile, the end of the drill rod away from the drill bit is provided with detachable connecting device, so that the mud discharging device and the grouting device can be quickly replaced when the drilling and grouting procedures are converted, different drill bits, mud discharging devices or grouting devices can be replaced to adapt to various stratum conditions and engineering requirements, such as drilling in different hardness strata, grouting of different types of slurry, etc., and the versatility and flexibility of the device are enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a structural schematic diagram of the drill rod device of the embodiment of the present application;

[0020] Figure 2 FIG. 2 is an assembly schematic diagram of the drill rod device and the mud discharging device of the embodiment of the present application;

[0021] Figure 3 FIG. 3 is an assembly schematic diagram of the drill rod device and the grouting device of the embodiment of the present application;

[0022] Figure 4 FIG. 4 is a structural schematic diagram of the drill bit of the embodiment of the present application;

[0023] Figure 5This is a schematic diagram of the sludge removal device according to an embodiment of the present invention;

[0024] Figure 6 This is a schematic diagram of the grouting device according to an embodiment of the present invention.

[0025] In the diagram: 1-Drill rod; 2-Drill bit; 3-Drilling rig; 4-Grouting pipe; 5-Spiral conveyor belt; 6-Detachable connection device; 7-Blade; 8-First buffer tank; 9-Second buffer tank; 10-Sand pump; 11-First motor; 12-Second motor; 13-Spraying device; 14-First filter screen; 15-Material cup; 16-High-pressure pump; 17-Third buffer tank; 18-Fourth buffer tank; 19-First pressure gauge; 20-Second pressure gauge; 21-Gearbox; 22-Second filter screen; 23-Roller; 24-Casing. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0027] This invention provides an integrated high-pressure grouting device for drilling, comprising: a drill rod 1, a drill bit 2, a drilling rig 3, a mud removal device, and a grouting device.

[0028] like Figure 1 As shown, a grouting pipe 4 is installed inside the drill rod 1, and a spiral conveyor belt 5 is welded to the outer wall of the grouting pipe 4. The outer side of the spiral conveyor belt 5 is welded to the inner wall of the drill rod 1. The drill rod 1 and the drill bit 2 are connected by threads, and a detachable connection device 6 is provided at the end of the drill rod 1 away from the drill bit 2. When drilling with the device, the spiral conveyor belt 5 is connected to the mud removal device through the detachable connection device 6. When grouting with the device, the grouting pipe 4 is connected to the grouting device through the detachable connection device 6.

[0029] Specifically, in this embodiment of the invention, a grouting pipe 4 and a spiral conveyor belt 5 are simultaneously installed inside the drill rod 1, integrating drilling and grouting functions onto the same drill rod. This achieves dual functionality with a single rod, reducing the number of equipment and construction procedures, and improving construction efficiency. The spiral conveyor belt in this embodiment is made of high-chromium alloy steel. During rotation, the spiral structure of the conveyor belt effectively lifts and transports the soil and rock entering the drill rod 1. Compared to other types of conveyor belts, it can more continuously transport soil and rock from the bottom of the drill rod 1 to the mud removal device, improving mud removal efficiency, reducing the accumulation and blockage risk of mud inside the drill rod, and ensuring smooth drilling operations.

[0030] The drill pipe 1 is connected with the drill bit 2 through threads, facilitating installation, disassembly and replacement of the drill bit, and suitable drill bits can be selected according to different stratum conditions.

[0031] The end of the drill pipe 1 away from the drill bit 2 is provided with a detachable connecting device 6, so that the mud discharging device and the grouting device can be quickly and conveniently replaced when the drilling and grouting processes are switched, improving the utilization rate of the equipment and reducing the idle cost of the equipment.

[0032] The shell of the drill pipe 1 in the embodiment is hard, with a diameter of about 150 cm and a thickness of about 30 cm; the grouting pipeline 4 has a diameter of about 20 cm and a pipe column thickness of about 5 cm; the spiral conveyor belt 5 has a width of about 30 cm; and the detachable connecting device is a buckle type quick connector made of aluminum alloy.

[0033] As shown in Figure 2 , during drilling, the spiral conveyor belt 5 is connected with the mud discharging device through the detachable connecting device 6, so that the soil and stones generated during the drilling process can be effectively discharged in time, avoiding the accumulation of soil and stones to affect the drilling progress. As shown in Figure 3 , during grouting, the grouting pipeline 4 is connected with the grouting device through the detachable connecting device 6, ensuring that the slurry is smoothly injected into the target area, and the entire construction process is orderly, reducing the construction time and labor cost.

[0034] The drill bit 2 includes a plurality of blades 7, as shown in Figure 4 , the blades 7 are arranged in a spiral around the central axis of the drill bit 2, and a certain distance is maintained between adjacent blades.

[0035] Specifically, the blades 7 are arranged in a spiral around the central axis of the drill bit 2, and can continuously cut the stratum when the drill bit 2 rotates, compared with non-spiral arranged blades, can more effectively break the stratum rock and soil, improve the efficiency and speed of drilling, and make the drilling process more smooth. At the same time, the spiral arrangement of the blades makes the drill bit bear force more evenly during drilling. Each blade bears similar cutting force at different times, avoiding the situation that the local force is too large or too small, so that the drill bit maintains a stable direction during drilling, reduces the deviation of the drilling trajectory, helps to improve the accuracy and quality of drilling, and meets the requirements of the project on the drilling perpendicularity or specific direction.

[0036] A certain distance is maintained between adjacent blades to form gaps, and the broken soil and stones can smoothly enter these channels during drilling. With the rotation and advancement of the drill bit 2, the soil and stones will enter the inside of the drill pipe 1 along the channels, avoiding the accumulation of soil and stones around the drill bit, preventing the drilling progress from being affected due to soil and stone blockage, and ensuring the continuity of the drilling operation.

[0037] As shown in Figure 5As shown, the sludge discharge device includes a first buffer tank 8, a second buffer tank 9, a sand and stone pump 10, a first motor 11 and a second motor 12. The soil and stones enter the sludge discharge device through the spiral conveyor belt 5. The bottom of the first buffer tank 8 is connected with the drill rod 1 through detachable connecting device. The first buffer tank 8, the second buffer tank 9 and the sand and stone pump 10 are connected through pipelines. The second buffer tank 9 is connected with the first motor 11. The sand and stone pump 10 is connected with the second motor 12.

[0038] Specifically, by setting the first buffer tank 8 and the second buffer tank 9, the soil and stones enter the first buffer tank 8 from the drill rod 1 and then flow into the second buffer tank 9. The two-stage buffer structure can effectively stabilize the flow state of the soil and stones, avoid the impact on the subsequent equipment caused by the sudden change of the soil and stone flow and pressure, and ensure the smooth progress of the entire sludge discharge process. The sand and stone pump 10 is driven by the second motor 12 and can provide strong suction and pressure to extract the soil and stones in the buffer tank and transport them to the designated position, ensuring that the soil and stones can overcome the pipeline resistance and gravity and other factors to be smoothly discharged. The second buffer tank 9 is connected with the first motor 11 and works cooperatively with the sand and stone pump 10 to improve the efficiency and effect of sludge discharge, speed up the sludge discharge speed, reduce the residence time of the soil and stones in the device, and thus improve the overall efficiency of the drilling operation.

[0039] The top of the first buffer tank 8 is provided with a spraying device 13.

[0040] Specifically, the soil and stones generated during the drilling of the device enter the drill rod 1 through the gap between the blades, and the spraying device 13 is used to convert the soil and stones into slurry. During the drilling process, the soil and stones entering the drill rod form slurry and are then conveyed to the first buffer tank. The water flow sprayed by the spraying device can convert the soil and stones into slurry, and the soil and stones after being converted into slurry can be discharged more quickly through the sludge discharge device. Since the slurry can be uniformly distributed in the pipeline and buffer tank and other components, it can be more efficiently transported out under the action of the sand and stone pump 10. Compared with directly processing solid soil and stones, processing slurry reduces the limitation on the size and shape of soil and stone particles, and the sludge discharge system can work at a more stable speed and flow, thereby improving the sludge discharge efficiency of the entire device.

[0041] When the solid soil and stones are transported in the equipment, they may cause wear and tear to the equipment due to collision, friction and other factors, especially to the inner wall of the pipeline and the pump body and other components. After the soil and stones are converted into slurry, the intense friction and collision between solids and between solids and equipment are reduced, the degree of wear and tear of the equipment is reduced, the service life of the sludge discharge device is prolonged, the frequency of equipment maintenance and replacement is reduced, and the construction cost is reduced.

[0042] A first filter screen 14 is arranged between the second buffer tank 9 and the first motor 11.

[0043] Specifically, the first filter screen 14 can effectively intercept larger particles or other impurities in the slurry, preventing these impurities from entering the first motor 11, thereby protecting the normal operation of the motor and reducing the possibility of motor failure due to impurity wear or blockage.

[0044] As shown in Figure 6 The grouting device includes a cup barrel 15, a high-pressure pump 16, a third buffer tank 17, and a fourth buffer tank 18. The bottom of the third buffer tank 17 is connected to the drill pipe 1 through detachable connecting devices. The third buffer tank 17, the fourth buffer tank 18, and the cup barrel 15 are connected through pipelines. The high-pressure pump 16 is arranged between the fourth buffer tank 18 and the cup barrel 15.

[0045] Specifically, the high-pressure pump 16 is arranged between the fourth buffer tank 18 and the cup barrel 15, which can provide stable pressure for the slurry, ensure the stable flow of the slurry in the pipeline, and accurately control the grouting pressure. By adjusting the parameters of the high-pressure pump 16, the slurry can be injected into the target area at an appropriate pressure according to different engineering requirements and formation conditions, improving the grouting effect and engineering quality.

[0046] The third buffer tank 17 and the fourth buffer tank 18 play a role in multi-stage buffering. The slurry in the cup barrel 15 first flows into the fourth buffer tank 18, then enters the third buffer tank 17, and finally is injected into the drill pipe 1. In this process, the buffer tank can balance the flow and pressure fluctuations of the slurry, prevent grouting interruption or instability caused by uneven slurry supply or pressure surge, and ensure the continuity of grouting operations.

[0047] A first pressure gauge 19 is arranged between the third buffer tank 17 and the fourth buffer tank 18. A second pressure gauge 20 is arranged between the fourth buffer tank 18 and the cup barrel 15. A gearbox 21 is arranged on the pipeline between the fourth buffer tank 18 and the cup barrel 15. The high-pressure pump 16 is connected to the gearbox 21.

[0048] Specifically, the first pressure gauge 19 and the second pressure gauge 20 can monitor the pressure changes between the third buffer tank 17 and the fourth buffer tank 18 and between the fourth buffer tank 18 and the cup barrel 15 in real time. The first pressure gauge 19 and the second pressure gauge 20 are connected to an intelligent pressure monitoring system, which issues a warning before the pressure approaches the pressure threshold. The operator can timely understand the pressure conditions at different stages of the grouting process according to these pressure data, so as to take prompt measures for adjustment when the pressure is abnormal, ensure that the grouting pressure is always within the appropriate range, and guarantee the grouting effect and engineering quality.

[0049] The gearbox 21 connects the high-pressure pump 16, and the speed and torque of the high-pressure pump 16 can be adjusted through the gearbox 21. Different slurry characteristics and grouting conditions may require different pump output parameters, and the gearbox 21 can adapt the high-pressure pump according to the actual situation.

[0050] The second filter screen 22 is arranged between the material cup barrel 15 and the fourth buffer tank 18.

[0051] Specifically, the second filter screen 22 can intercept impurities in the slurry flowing from the material cup barrel 15 to the fourth buffer tank 18, prevent larger particles or other impurities from entering the subsequent equipment, avoid problems such as wear and tear and blockage of the equipment, and ensure the normal operation of the equipment.

[0052] The fourth buffer tank 18 is provided with a roller 23 at the bottom.

[0053] Specifically, the arrangement of the roller 23 makes the movement of the grouting device between the construction site or different work areas extremely convenient. Without the help of large lifting equipment or the consumption of a large amount of manpower for carrying, it can easily change its position by pushing or pulling, greatly improving the mobility and flexibility of the equipment, saving the time and labor cost of equipment transfer. During the construction process, it may be necessary to adjust the layout of the grouting device according to the actual situation on site. The roller 23 can conveniently change the relative position of the grouting device, make the layout of the entire grouting device more reasonable, adapt to different construction site conditions and process flow requirements, help to optimize the construction operation process, and improve the construction efficiency.

[0054] A casing 24 is arranged around the drill pipe 1 near the ground.

[0055] Specifically, during the drilling process, the casing 24 can prevent the hole wall from collapsing. Especially in soft or collapsible strata, the casing 24 can provide lateral support to maintain the shape and stability of the hole wall, ensure the safe progress of the drilling operation, and avoid problems such as drilling failure and equipment damage caused by hole wall collapse. At the same time, the casing 24 can effectively isolate surface water, prevent surface water from flowing into the drill hole, avoid changes in the properties of the drilling mud or water accumulation in the hole, affect the normal progress of drilling and subsequent construction, maintain the stability of the drilling mud and the liquid level in the hole, and ensure the smooth development of the mud discharge and grouting processes.

[0056] The device of the present application comprises the following steps when actually used:

[0057] S1, check whether the equipment is in normal working condition.

[0058] S2, connect the grouting pipeline and the first buffer tank through the buckle type detachable connecting device, and then start the drilling machine.

[0059] S3, start the spiral rising conveyor belt, as the drill bit drills, the mud will enter the first buffer tank through the spiral rising conveyor belt, and will be discharged under the action of the sand pump and the first motor, a fluororesin coating is applied to the formed drill hole wall, and the wear condition is checked regularly.

[0060] S4, the first buffer tank is separated from the buckle type detachable connecting device, and a third buffer tank of the grouting device is replaced.

[0061] S5, the used slurry is added into the cup barrel, the high-pressure pump is started, the slurry is conveyed to the fourth buffer tank through the grouting pipeline, finally enters the target area through the grouting pipeline in the drill rod, and the pressure in the pipeline is monitored through the first high-pressure gauge and the second high-pressure gauge during the period, so that the grouting is ensured to be carried out smoothly.

[0062] The drilling device and the grouting device are combined, one rod is used for two purposes, the limitation of the existing high-pressure grouting technology is effectively solved, the drilling and grouting equipment is integrated, the operation is more convenient, the space is saved, the work efficiency is improved, the steps of twice carrying and installing equipment are saved, the cost is reduced, and the construction period is shortened.

[0063] The technical features of the above embodiments can be combined arbitrarily, in order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, only the preferred embodiments of the present application are expressed, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the present application. As long as the combination of these technical features does not exist, it should be considered that it is within the scope of the present application.

[0064] It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A drilling and high-pressure grouting integrated device, characterized in that, The utility model relates to a drilling device, including: Drill rod (1), drill bit (2), drilling machine (3), sludge discharging device and grouting device, the inside of drill rod (1) is equipped with grouting pipeline (4), the outer wall of grouting pipeline (4) is welded with spiral conveyor belt (5), the outside of spiral conveyor belt (5) is welded with the inner wall of drill rod (1), drill rod (1) is connected through screw thread between drill bit (2), the one end of drill rod (1) away from drill bit (2) is provided with detachable connecting device (6), when drilling, spiral conveyor belt (5) is connected with sludge discharging device through detachable connecting device (6), when grouting, grouting pipeline (4) is connected with grouting device through detachable connecting device (6), The sludge discharging device includes first buffer pool (8), second buffer pool (9), sand and stone pump (10), first motor (11) and second motor (12), the bottom of first buffer pool (8) is connected with drill rod (1) through detachable connecting device (6), first buffer pool (8), second buffer pool (9) and sand and stone pump (10) are connected through pipeline, second buffer pool (9) is connected with first motor (11), sand and stone pump (10) is connected with second motor (12), The grouting device includes cup barrel (15), high pressure pump (16), third buffer pool (17), fourth buffer pool (18), the bottom of third buffer pool (17) is connected with drill rod (1) through detachable connecting device, third buffer pool (17), fourth buffer pool (18) and cup barrel (15) are connected through pipeline, high pressure pump (16) is arranged between fourth buffer pool (18) and cup barrel (15).

2. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: The drill bit (2) includes a plurality of blades (7), the blades (7) are arranged around the central axis of the drill bit (2) in a spiral manner, and a certain spacing is maintained between adjacent blades.

3. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: The top of the first buffer pool (8) is provided with a spraying device (13).

4. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: A first filter screen (14) is provided between the second buffer pool (9) and the first motor (11).

5. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: A first pressure gauge (19) is provided between the third buffer pool (17) and the fourth buffer pool (18), a second pressure gauge (20) is provided between the fourth buffer pool (18) and the cup barrel (15), a gearbox (21) is provided on the pipeline between the fourth buffer pool (18) and the cup barrel (15), and the high pressure pump (16) is connected to the gearbox (21).

6. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: A second filter screen (22) is provided between the cup barrel (15) and the fourth buffer pool (18).

7. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: The bottom of the fourth buffer pool (18) is provided with a roller (23).

8. The integrated drilling and high-pressure grouting device according to claim 1, characterized in that: A casing (24) is provided around the drill rod (1) near the ground.

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