A high-efficiency and low-cost trenching method for rapid construction of hard rock wall

Abstract

The application discloses a kind of hard rock layer efficient low-cost wall fast construction slotting method, it is related to underground continuous wall or cutoff wall construction technical field, comprising the following steps: S01, by electric rotary drilling rig in the axis of design wall is carried out wall pilot hole construction according to predetermined interval, form multiple pilot holes through hard rock layer, then adopt the special self-driven milling slotting drill bit of rotary drilling for wall washing slotting is formed.The application greatly reduces the access threshold and fixed asset investment of such engineering construction enterprise, only needs to adopt electric rotary drilling rig to complete hard rock layer underground wall construction, adopts electric rotary drilling rig, and mechanical power cost can be saved by about 65%, adopts the special self-driven washing slotting drill bit of modified rotary drilling machine to replace traditional large double-wheel milling equipment, realizes rotary drilling rig one machine dual use, and large double-wheel milling equipment is no longer needed to be configured, single set of slotting equipment cost is saved by more than 75%, under single set of slotting equipment working condition, compared with traditional double-wheel milling slotting scheme, the new construction method can save more than 60% of construction cost as a whole, and realizes fast slotting construction.

Description

Technical Field

[0001] This invention relates to the field of construction technology for underground continuous walls or seepage-proof walls, specifically a method for rapid trenching construction of walls in hard rock strata with high efficiency and low cost. Background Technology

[0002] In fields such as water conservancy and hydropower, building foundation pits, and municipal engineering, it is often necessary to construct diaphragm walls or seepage barriers in hard or extremely hard rock strata (such as conglomerate, sandstone, argillaceous limestone, and granite). Currently, the main technical approaches for trenching construction in such hard rock strata are as follows: One method is the percussion drilling trenching method (refer to Chinese authorized patent, publication number CN104196044B, publication date 2016-01-20, which discloses a cofferdam construction method combining percussion drilling with milling and steel sheet piles). Although this method is applicable to all rock strata, the construction speed is extremely slow and it is accompanied by huge noise and vibration, making it unsuitable for use near existing buildings or in areas with high environmental protection requirements.

[0003] The second method is the combination of pre-drilling and dual-wheel milling to form a groove (refer to Chinese patent publication, publication number CN115822013A, publication date 2023-03-21, which discloses a dual-wheel milling machine milling wheel). This method first uses a traditional fuel-powered rotary drilling rig to pre-drill holes, and then uses a large dual-wheel milling machine to mill the groove. This method is fast and suitable for hard rock, but it has a fatal flaw: the dual-wheel milling equipment is extremely expensive. Traditional fuel-powered rotary drilling rigs and large dual-wheel milling machines are driven by high-power diesel engines, resulting in high fuel costs.

[0004] Third, methods such as pre-drilling and impact drilling also present significant issues regarding cost and efficiency.

[0005] In summary, existing trenching techniques for hard rock formations generally suffer from inherent problems such as extremely high equipment costs, high power consumption costs, low construction efficiency, and environmental unfriendliness. A significant solution is needed to substantially reduce equipment investment costs and power costs during construction while ensuring the efficiency and effectiveness of hard rock trenching. Summary of the Invention

[0006] The purpose of this invention is to provide a method for rapid construction of trenches in hard rock strata with high efficiency and low cost, so as to overcome the above-mentioned shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for rapid trenching construction of walls in hard rock strata with high efficiency and low cost, comprising the following steps: S01. Using an electric rotary drilling rig, pre-holes are drilled along the axis of the designed wall at predetermined intervals to form multiple pre-holes that penetrate the hard rock layer. S02. After the pilot hole is completed, the working parts of the electric rotary drilling rig are replaced from the rotary drilling bit to a rotary drilling-specific self-driven trenching drill bit. Then, reciprocating milling and trenching are performed along the connecting direction of multiple pilot holes to make adjacent pilot holes interconnect and expand, ultimately forming a continuous trench segment that meets the design requirements. S03. Repeat steps S01 and S02 above until the construction of all sections of the entire underground continuous wall or seepage barrier is completed.

[0008] Preferably, a 380V industrial mains power supply network that meets the power requirements of the electric rotary drilling rig needs to be built before step S01 is performed.

[0009] Preferably, the predetermined spacing in step S01 is determined based on the working dimensions of the special grooving drill bit, ensuring that the width of the uncut rock mass between two adjacent pilot holes is less than or equal to the maximum single milling width of the special grooving drill bit.

[0010] Preferably, the milling and washing process performed in S02 is performed according to the following steps: starting from the top of each trench segment, milling downwards to a preset depth, then raising the self-driven trench washing drill bit of the rotary drilling rig, then moving laterally by one milling width, and continuing to mill downwards until the milling of all areas of the wall trench segment is completed; then entering the next wall trench segment, repeating the above process, until the designed trenching depth and single trenching pouring width of the trench segment are reached.

[0011] Preferably, while milling the groove in step S02, wall-protecting mud is injected into the excavated groove through the mud pipeline, and the milled rock cuttings are carried out by the pneumatic mud reverse circulation method of the self-driven milling drill bit, so as to maintain the stability of the groove wall and clean the rock cuttings at the bottom of the groove to ensure continuous milling by the drill bit.

[0012] Preferably, the reciprocating milling and washing in step S02 refers to the washing drill bit performing horizontal lateral swing cutting between two adjacent pilot holes, while simultaneously performing vertical up-and-down lifting cutting, forming a two-dimensional composite motion to break the residual rock ridges between the pilot holes and the remaining rock mass in the trench excluding the pilot holes.

[0013] Preferably, the trough-washing drill bit is a wheel-type trough-washing drill bit.

[0014] Preferably, the trenching drill bit includes a housing, which is assembled and connected to the bottom square head of the telescopic drill rod of the electric rotary drilling rig via a quick connector fixedly installed at the top. A bottom compartment is fixedly installed at the bottom, and a first power wheel and a second power wheel, which are rotatably arranged on the same horizontal plane on opposite sides of the bottom compartment. Alloy tracks are fitted on the first power wheel and the second power wheel. The alloy tracks are composed of several connecting blocks that are hinged together end to end, and each connecting block has a toothed seat fixedly installed on its surface, which is equipped with a cutting tooth drill bit. The sidewall of the lower compartment is rotatably provided with at least two support wheels located between the first and second drive wheels, which are rolledly connected to the side of the alloy track that contacts the ground.

[0015] Preferably, the cabin has recessed channels, and the cutting teeth on the alloy track during circumferential movement travel within the recessed channels. The chamber is fixedly connected to a mud slurry pipe, and the chamber includes: The first output port, located within the recessed channel, consists of two sets of third nozzles with opposite tilting directions, and the output direction of the third nozzles is the entrance of the cutting teeth into the recessed channel and the exit of the recessed channel. Located at the bottom of the cabin and between the alloy tracks on both sides, there are two rows of spaced second output ports. Each of the multiple second output ports on one side is divided into a first nozzle and a second nozzle. The multiple first nozzles and multiple second nozzles are spaced apart and their output direction is towards the alloy tracks and symmetrically distributed in the vertical direction about the axis of the drive wheel.

[0016] Preferably, a drive shaft is rotatably installed inside the bottom compartment, and a worm gear fixedly installed on the drive shaft meshes with the worm wheel at the output end of a hydraulic motor and a reducer fixedly installed inside the compartment. A first trapezoidal gear fixedly mounted on the shaft end of the two first drive wheels / two second drive wheels meshes with a second trapezoidal gear fixedly mounted on the end of the transmission shaft.

[0017] The present invention provides a method for rapid trenching construction of walls in hard rock strata at high efficiency and low cost, which has the following beneficial effects: First, a pilot hole is quickly formed using an electric rotary drilling rig, creating ample free surface for cutting hard rock. Then, the two-dimensional composite motion (horizontal oscillation + vertical lifting) of the grooving drill bit is used for efficient milling. Combined with a layered grooving process, ineffective crushing is avoided. Its overall grooving speed is significantly faster than traditional impact drilling. In medium to high hardness rock formations, it can approach or reach the efficiency level of twin-wheel milling, completely replacing large twin-wheel milling equipment with a low-cost grooving drill bit.

[0018] The pilot hole provides guidance for the drill bit, preventing it from deviating. Synchronous injection of wall-protecting mud and an innovative high-pressure nozzle layout ensure trench wall stability, trench bottom cleanliness, and drill bit cleaning during milling. Layered, reciprocating milling paths guarantee the flatness and verticality of the trench walls, meeting high standards for seepage prevention and load-bearing capacity.

[0019] Compared to the traditional twin-wheel milling trenching method, it can save more than 60% of the construction cost and achieve rapid trenching construction. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a schematic diagram of the process structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the tank cleaning drill bit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the transmission structure provided in an embodiment of the present invention; Figure 4 The diagram shows the structure of the first output port and the second output port provided in the embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Sinking drill bit; 2. Cabin; 21. Quick connector; 22. Recessed channel; 23. Mud slurry pipe; 231. First output port; 232. Second output port; 3. Bottom compartment; 31. First drive wheel; 32. Second drive wheel; 33. Alloy track; 34. Support wheel; 40. Drive shaft; 41. Worm gear; 42. Worm wheel; 43. First trapezoidal gear; 44. Second trapezoidal gear. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] Please see Figure 1-4 This invention provides a technical solution: a method for rapid trenching construction of walls in hard rock strata with high efficiency and low cost, comprising the following steps: S01. First, determine the axis of the diaphragm wall or seepage barrier to be constructed according to the design drawings. Then, use an electric rotary drilling rig to construct pilot holes along this axis at predetermined intervals. The electric rotary drilling rig drills downwards, penetrating the hard rock layer, forming multiple vertical, cylindrical pilot holes. These pilot holes provide the initial free surface and guiding space for subsequent through-milling, reducing the hard rock milling area and accelerating the subsequent hard rock milling speed.

[0025] In a preferred embodiment, to significantly reduce energy consumption and operating costs during construction, a new type of electrically driven rotary drilling rig is used. Before performing step S01, a 380V industrial mains power grid needs to be established at the construction site to provide stable and inexpensive power for the electrically driven rotary drilling rig and subsequent trenching operations. Compared to traditional diesel-driven rotary drilling rigs and twin-wheel milling machines, the electric drive solution can reduce the overall power cost of underground wall construction by approximately 65%.

[0026] S02. After completing the construction of all predetermined pilot holes in the wall, remove the pilot hole drill bit from the drill rod of the electric rotary drilling rig and replace it with a dedicated trenching drill bit 1. Then, start the electric rotary drilling rig and drive the trenching drill bit 1 to perform reciprocating milling and trenching operations along the line connecting the multiple pilot holes. The cutting components of the trenching drill bit 1 can break the rock ridge between two adjacent pilot holes and the remaining rock mass in the trench except for the pilot holes, so that the pilot holes are interconnected and continuously expand to both sides, eventually forming a continuous trench segment with cross-sectional dimensions that meet the design requirements.

[0027] To ensure the quality and efficiency of trenching, the predetermined spacing between the pilot holes in step S01 is not a fixed value, but is determined based on the effective working capacity of the dedicated trenching drill bit 1 and the size of the milling drill bit. Specifically, the center distance between two adjacent pilot holes should be designed such that the maximum width of the uncut rock mass between the two pilot holes (i.e., the shortest distance between the two hole walls) is less than or equal to the maximum single milling width of the trenching drill bit 1. This ensures that the drill bit can completely remove all residual rock mass between the pilot holes, avoiding leaving any uncuttable dead corners.

[0028] In a more specific implementation of layered milling, the milling and washing processes in step S02 above are performed according to the principle of layered, horizontal reciprocating milling: First, starting from the top plane of the trench section, the washing drill bit 1 is lowered to the preset first layer depth. Then, starting from the edge of a pilot hole, the drill bit is moved laterally to mill a working width of rock layer. After completing this width, it is moved laterally by a milling width distance and continues to mill adjacent areas of the same depth layer downwards. This process is repeated until all areas of the layer are milled. After completing one layer, the washing drill bit 1 is lowered to the next depth layer, and the above horizontal reciprocating milling process is repeated until the designed depth of the trench section is reached. This layered trenching process effectively controls the load of a single cut, ensuring the stability of the drill bit and the main body of the electric rotary drilling rig.

[0029] S03. Repeat steps S01 and S02 above to complete the drilling and milling of each section of the entire underground continuous wall or seepage barrier in sequence, until all sections are completed and a complete underground continuous wall is formed.

[0030] In another preferred embodiment, to further improve trenching efficiency and trench wall stability, while milling the trench in step S02, wall-protecting mud is continuously injected into the excavated trench through mud pipes installed at the top of the trench on the construction plane. The mud forms a dense mud cake on the trench wall, effectively preventing trench wall collapse. Simultaneously, the mud circulates within the trench, carrying away broken rock fragments to the bottom, where they are purified by a surface mud treatment system and reused, maintaining the cleanliness of the trench bottom and ensuring trenching accuracy.

[0031] Furthermore, the reciprocating milling and washing process is not simply a matter of vertical lowering and horizontal movement. Instead, it refers to the specialized washing drill bit 1 performing horizontal lateral oscillating cutting between two adjacent pilot holes, while simultaneously performing vertical up-and-down lifting cutting. These two movements are superimposed, forming a two-dimensional composite motion. This motion allows the cutting teeth on the drill bit to repeatedly break the remaining rock ridges and the remaining rock mass in the groove (excluding the pilot holes) at varying cutting angles, avoiding the cutting dead angles or drill jamming that may occur with unidirectional cutting, and greatly improving the breaking efficiency and cutting uniformity.

[0032] To achieve the aforementioned low-cost, high-efficiency trenching method, this invention also discloses a preferred dedicated trenching drill bit 1. In one specific embodiment, the trenching drill bit 1 is a wheel-type trenching drill bit. Please refer to the accompanying drawings as follows. Figure 2-4 Its specific structure and connection relationships are as follows: The trenching drill bit 1 comprises a hollow chamber 2. A quick connector 21 is fixedly mounted on the top of the chamber 2 for quick and secure assembly with the telescopic drill rod of an electric rotary drilling rig. A bottom chamber 3 is fixedly mounted on the bottom of the chamber 2 by welding or bolting.

[0033] On the opposite side walls of the bottom compartment 3, a first drive wheel 31 and a second drive wheel 32 are rotatably mounted. The axis lines of the first drive wheel 31 and the second drive wheel 32 are on the same horizontal plane to ensure synchronous operation. A closed alloy track 33 is tightly fitted onto the first drive wheel 31 and the second drive wheel 32 on the same side. The alloy track 33 is composed of several high-hardness connecting blocks that are hinged together end to end, and each connecting block has a tooth seat fixedly installed on its outer surface. Each tooth seat has a cutting tooth for cutting rock fixedly installed in it through an assembly fit connection.

[0034] To support the alloy track 33 and prevent it from deforming under heavy loads, at least two support wheels 34 are rotatably mounted on the side wall of the base 3. These support wheels 34 are located between the first drive wheel 31 and the second drive wheel 32, and their wheel surfaces are rolledly connected to the inner surface of the alloy track 33 on the side that contacts the ground and is used for cutting. This support structure greatly enhances the rigidity and stability during cutting.

[0035] In another, more specific embodiment, to achieve efficient slag removal and cutting tooth cooling, a recessed channel 22 is provided on the chamber 2. The upper part of the alloy track 33, moving circumferentially, passes through this recessed channel 22, allowing rock cuttings adhering to the cutting teeth to be removed by subsequent structures. Simultaneously, a mud slurry pipe 23 for injecting high-pressure mud is fixedly connected to the chamber 2. The chamber 2 also integrates a dedicated mud slurry nozzle, including: The first output port 231 is located inside the recessed channel 22. This port consists of two sets of third nozzles with opposite inclination directions. One set of third nozzles is aligned with the entrance of the cutting tooth into the recessed channel 22, while the other set is aligned with the exit of the cutting tooth through the recessed channel 22. When the alloy track 33 is in operation, high-pressure mud powerfully washes the cutting tooth from these two directions. This not only cleans the rock powder adhering to the cutting tooth to prevent mud from clogging the drill and hindering rock cutting, but also agitates the milling layer mud, making it easier for mud and rock debris to enter the slag suction port inside the drill bit and aiding in slag removal.

[0036] The second output ports 232 are located at the bottom of the hull 2 ​​and within the space between the two alloy tracks 33. These ports are arranged in two rows at intervals. Each row of multiple second output ports 232 is further divided into first nozzles and second nozzles, with multiple first nozzles and multiple second nozzles arranged alternately. The output direction of the first nozzles is towards one side of the alloy track 33, and the output direction of the second nozzles is towards the other side of the alloy track 33. Furthermore, the spray directions of both are symmetrically distributed vertically about the axis of the drive wheel. This design allows the mud sprayed from the bottom of the hull 2 ​​to directly wash over the rock debris cut by the tracks on both sides, forming an effective bottom mud circulation flow. This efficiently removes rock debris from the center of the trough bottom, preventing secondary breakage.

[0037] Regarding the driving method of the aforementioned power wheels 31 and 32, a specific embodiment is as follows: A drive shaft 40 is rotatably mounted within the bottom compartment 3 via bearings. A worm gear 41 is fixedly mounted on the drive shaft 40. At least two sets of high-power hydraulic motor and reducer drive systems are fixedly mounted within the compartment 2, and a worm wheel 42 is fixedly mounted at the output end of the reducer. The worm gear 41 and the worm wheel 42 are meshed together. When the hydraulic motor and reducer are started, the worm wheel 42 drives the worm gear 41 to rotate, thereby driving the drive shaft 40 to rotate.

[0038] Furthermore, a first trapezoidal gear 43 is fixedly mounted on the axle ends of the two opposing first drive wheels 31 and the axle ends of the two second drive wheels 32. A second trapezoidal gear 44 is fixedly mounted on each end of the drive shaft 40. Each second trapezoidal gear 44 meshes with the first trapezoidal gear 43 on the same side of the first drive wheel 31 or second drive wheel 32. Through this efficient hydraulic motor reducer and trapezoidal gear-worm gear transmission mechanism, the alloy tracks 33 on both sides can be driven synchronously, smoothly, and with high torque for rotary cutting, achieving compact power transmission and high reliability.

[0039] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for rapid trenching construction of walls in hard rock strata with high efficiency and low cost, characterized in that, Includes the following steps: S01. Using an electric rotary drilling rig, pre-holes are drilled along the axis of the designed wall at predetermined intervals to form multiple pre-holes that penetrate the hard rock layer. S02. After the pilot hole is completed, the working parts of the electric rotary drilling rig are replaced with a troughing drill bit (1) instead of a rotary drilling bit. Then, reciprocating milling and troughing are performed along the connecting direction of the multiple pilot holes to make the adjacent pilot holes interconnect and expand, and finally form a continuous trough segment that meets the design requirements. S03. Repeat steps S01 and S02 above until the construction of all sections of the entire underground continuous wall or seepage barrier is completed.

2. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 1, characterized in that, Before performing step S01, a 380V industrial mains power supply network that meets the power requirements of the electric rotary drilling rig needs to be built.

3. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 1, characterized in that, The predetermined spacing in step S01 is determined based on the working dimensions of the special trenching drill bit, ensuring that the width of the uncut rock mass between two adjacent pilot holes is less than or equal to the maximum single milling width of the rotary drilling special self-driven trenching drill bit.

4. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 1, characterized in that, The milling and washing process performed in S02 is carried out according to the following steps: starting from the top of each trench segment, milling downwards to the preset depth, then lifting the special self-driven trench washing drill bit (1) of the rotary drilling machine, then moving laterally by one milling width, and continuing to mill downwards until the milling of all areas of the wall trench segment is completed; then entering the next wall trench segment, repeating the above process until the designed trenching depth and single trenching pouring width of the trench segment are reached.

5. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 4, characterized in that, While milling the groove in step S02, wall-protecting mud is injected into the excavated groove through the mud pipeline, and the milled rock cuttings are carried out by the pneumatic mud reverse circulation method of the self-driven milling drill bit to maintain the stability of the groove wall and clean the rock cuttings at the bottom of the groove to ensure continuous milling by the drill bit.

6. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 5, characterized in that, The reciprocating milling and washing mentioned in step S02 refers to the self-driven troughing drill bit (1) performing horizontal lateral swing cutting between two adjacent pilot holes, while simultaneously performing vertical up-and-down lifting cutting, forming a two-dimensional composite motion to break the residual rock ridges between the pilot holes and the remaining rock mass in the trough except for the pilot holes.

7. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 1, characterized in that, The trough-washing drill bit (1) is a wheel-type trough-washing drill bit.

8. The method for rapid trenching construction of hard rock strata walls with high efficiency and low cost according to claim 1, characterized in that, The trenching drill bit (1) includes a cabin (2), which is assembled and connected to the bottom square head of the telescopic drill rod of the electric rotary drilling rig through a quick connector (21) fixedly installed on the top. A bottom compartment (3) is fixedly installed on the bottom compartment (3). The bottom compartment (3) is rotatably provided with a first power wheel (31) and a second power wheel (32) on the same horizontal plane on opposite sides. Alloy tracks (33) are provided on the first power wheel (31) and the second power wheel (32). The alloy tracks (33) are composed of several connecting blocks that are hinged together at both ends. Each connecting block has a tooth seat fixedly installed on its surface, which is equipped with a cutting tooth drill bit. The side wall of the bottom compartment (3) is rotatably provided with at least two support wheels (34) distributed between the first power wheel (31) and the second power wheel (32), which are rolledly connected to the side of the alloy track (33) that contacts the ground.

9. A method for rapid trenching construction of hard rock strata with high efficiency and low cost, as described in claim 7, characterized in that, The cabin (2) has a recessed channel (22), and the cutting teeth on the alloy track (33) moving in the circumferential direction pass through the recessed channel (22); The chamber (2) is fixedly connected to a mud slurry pipe (23), and the chamber (2) includes: The first output port (231) located in the recessed channel (22) consists of two sets of third nozzles with opposite tilt directions, and the output direction of the third nozzle is the entrance of the cutting tooth into the recessed channel (22) and the exit of the recessed channel (22); Located at the bottom of the cabin (2) and between the alloy tracks (33) on both sides, there are two rows of spaced second output ports (232). Multiple second output ports (232) on one side are divided into first nozzles and second nozzles. Multiple first nozzles and multiple second nozzles are spaced apart. Their output direction is towards the alloy track (33) and they are symmetrically distributed in the vertical direction about the center of the drive wheel.

10. A method for rapid trenching construction of hard rock strata with high efficiency and low cost, as described in claim 7, characterized in that, A drive shaft (40) is rotatably installed inside the bottom compartment (3). A worm gear (41) fixedly installed on the drive shaft (40) meshes with the worm wheel (42) at the output end of the hydraulic motor and reducer fixedly installed inside the compartment (2). The first trapezoidal gear (43) fixedly mounted on the shaft ends of the two first power wheels (31) / two second power wheels (32) meshes with the second trapezoidal gear (44) fixedly mounted on the end of the transmission shaft (40).

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