Construction method and construction equipment for precisely excavating rock foundation pit by impact splitting

Abstract

A construction method and construction equipment for precisely excavating a rock foundation pit by impact splitting, specifically comprising the following steps: S1, demarcating the foundation pit range; marking the foundation pit edge according to the design line, dividing a plurality of annular excavation lines from the center of the foundation pit to the edge of the foundation pit within the foundation pit range, the interval between adjacent excavation lines being a construction width L2, a drilling position is marked along the excavation line by a construction worker, the interval between the drillings being L1, and finally the thickness D of the foundation pit soil layer excavated each time is determined; S2, excavating the foundation pit; first, drilling the drilling position marked on the excavation line, then inserting a splitting machine into the drilling, and splitting the drilling along the excavation line, the construction method of the present application improves the precision of foundation pit excavation, prevents over-excavation and under-excavation, and further improves the efficiency of foundation pit excavation in cooperation with the device of the present application.

Description

Technical Field

[0001] The present invention relates to the field of foundation pit and slope engineering excavation construction, and in particular to a construction method and construction equipment for impact splitting and precise excavation of a rock foundation pit. Background Art

[0002] In recent years, with the accelerating pace of urbanization in my country, urban land resources have become increasingly scarce, and urban construction has gradually shifted from surface to underground. The construction of high-rise buildings, subways, and large underground transportation hubs all rely on foundation pit engineering. Foundation pits have reached unprecedented scale in terms of area, depth, and length, while the surrounding environment has also grown increasingly complex. During foundation pit construction, localized over-excavation is unavoidable due to factors such as improper design, cost control, and ease of machinery installation. Accidents resulting from this localized over-excavation are a frequent occurrence.

[0003] For example: 1. The foundation pit slope protection piles overturned and became unstable due to the failure to install anchor rods when the pit bottom was excavated during construction; 2. In 2001, a composite soil nail support foundation pit in Jing'an District, Shanghai, caused two consecutive accidents due to two consecutive serious over-excavations, which eventually led to large-scale cracks in surrounding buildings and caused serious economic losses; 3. In 2008, the North 2 foundation pit of Hangzhou Metro Xianghu Station caused continuous collapse accidents due to over-excavation; 4. In 2009, a foundation pit in Baoshan District, Shanghai, suffered "kicking" damage to the retaining structure due to local over-excavation near the edge.

[0004] From the above accidents, it can be seen that over-excavation may cause various forms of instability and damage to the foundation pit. In order to save costs and shorten the construction period, the phenomenon of over-excavation of foundation pits often occurs. If the support is not timely, over-excavation will have a direct impact on the foundation pit and the foundation pit support. Specifically, if the foundation pit support is not in place, over-excavation will cause the shear stress of the soil to increase, the internal friction angle and cohesion between the soil particles to decrease, and the balance to lose, thus causing landslides or collapses. In severe cases, it will affect the life safety of workers in the foundation pit. As for the construction unit, the amount of over-excavation is an additional amount of work and will not be calculated in the total amount of work. In other words, the amount of excavation, backfill and corresponding labor costs in the over-excavation part need to be included in the loss. On the one hand, it leads to a significant reduction in the profit of the construction unit, and on the other hand, it will also affect the total construction period. There are no effective solutions in existing projects. Most solutions are to reinforce and support the over-excavated part to prevent landslides or collapses after over-excavation occurs, such as Chinese patent No. CN201810186642.3. The reinforcement and support content described in this technology and similar technologies are all post-reinforcement treatments.

[0005] For specific rock foundation pits, since the bedrock in most areas is directly exposed and has good integrity, the common rock types are granite, limestone, dolomite, quartzite, etc., which are hard and have high foundation bearing capacity, so the efficiency of ordinary mechanical excavation methods is not ideal. In engineering construction, it is necessary to take into account both safety and environmental protection. Among them, the excavation of foundation pit stone is a hot and difficult problem that troubles construction units. Although there is a method of excavating the foundation pit by blasting first and then mechanical excavation, due to the various anisotropic properties of the rock mass, this method has uncontrollable factors, which can easily destroy the stability of the slope and cause over-excavation. It is not an ideal method of foundation pit excavation. In addition, blasting excavation also has safety hazards. It requires specialized blasting personnel to operate, and it will produce noise pollution and toxic gases, which limits its use in excavation construction near cities. The process requires complex procedures and is also costly. At the same time, another preventive measure is that the surveying personnel will review the elevation at any time. The last layer of soil is excavated with a small excavator, and technical briefing is carried out. The soil is excavated to 30 centimeters from the bottom elevation for manual excavation. However, during actual construction, due to the large excavation area and wide range of the foundation pit, manual cleaning is difficult.

[0006] In summary, the existing technology still has the following problems:

[0007] (1) During the foundation pit construction process, due to improper design, control of construction costs and convenience of mechanical installation, local over-excavation of the foundation pit is difficult to avoid. Foundation pit damage accidents caused by local over-excavation occur frequently. The current construction technology cannot achieve accurate excavation of rock foundation pits.

[0008] (2) For specific rock foundation pits, since the bedrock in most areas is directly exposed and has good integrity, the common rock types are granite, limestone, dolomite, quartzite, etc., which have hard rock properties and high foundation bearing capacity, the efficiency of using ordinary mechanical excavation methods is not ideal.

[0009] (3) In the excavation of foundation pit stone, the existing construction technology cannot take into account both safety and environmental protection at the same time, and there are also disadvantages such as pollution and safety hazards.

[0010] In view of this, there is an urgent need to invent a construction method and a construction device that can solve the problem of over-excavation of foundation pits and achieve precise excavation of foundation pits. Summary of the Invention

[0011] The present invention solves the deficiencies of the prior art and provides a construction method for accurately excavating rock foundation pits by impact splitting, which improves the excavation accuracy of foundation pits and prevents over-excavation and under-excavation, as well as a drilling and splitting integrated machine for improving excavation efficiency.

[0012] A construction method for precise excavation of a rock foundation pit by impact splitting, specifically comprising the following steps:

[0013] S1: Delimit the scope of the foundation pit:

[0014] Mark the edge of the foundation pit according to the design line, then divide the foundation pit into multiple circular excavation lines from the center to the edge of the foundation pit. The interval between adjacent excavation lines is a construction width L2. Construction personnel mark the drilling positions along the excavation lines, with the drilling interval being L1. Finally, determine the foundation pit soil layer thickness D for each excavation.

[0015] S2: Excavation of foundation pit:

[0016] Excavate from the center of the foundation pit outward in sequence, with each excavation covering at least a construction width L2. Specifically, drill holes according to the drilling positions pre-marked on the excavation line, and the drilling depth matches the thickness D of the soil layer excavated each time. After drilling is completed, all holes are inspected and excess rock debris in the holes is cleaned. Then, a splitter is inserted into the hole, and the holes are split along the excavation line so that the cracks formed by the splitting pass through the adjacent holes along the excavation line. After the splitting is completed, an excavator is used to excavate the rock layer within the foundation pit excavation line. Repeat the above steps until one layer of foundation pit excavation is completed, and then proceed to excavate the next layer of foundation pit soil until the entire foundation pit is excavated.

[0017] In this embodiment, in step S1, the method for determining the drilling interval L1 is as follows:

[0018] a. First determine the relationship between the length l of the splitting head and the splitting force F:

[0019] Collect rock samples at the location of the construction pit, conduct strength tests on the rock samples, and classify the rock samples into hard rock (tensile strength ≥

[0020] 30 / MPa), medium-hard rock (tensile strength of 10-30 / MPa), and soft rock (tensile strength ≤10 / MPa); splitting tests were then conducted on rock samples to obtain the relationship between the length l of the splitting head and the splitting force F; the obtained multiple sets of data were substituted into Origin for nonlinear function fitting to obtain the function f(l) = F;

[0021] b. Determine the relationship between the splitting force F and the working distance L1 between adjacent splitters;

[0022] The minimum working spacing L1 is the sum of the extension lengths l of the splitting heads of adjacent splitters. Then, the empirical coefficient α is defined according to the tensile strength of the rock sample. Here, α = 3 for hard rock, α = 4 for medium-hard rock, and α = 5 for soft rock, resulting in:

[0023] L 1最大 =2αl; (1)

[0024] Substituting formula (1) into the function f(l)=F, we get the functional relationship f(L1)=F. When the working spacing L1 of the splitter can meet the strength of the corresponding rock to be split, the maximum value of L1 in the function f(L1)=F is selected as the working spacing of the splitter, and this spacing is the interval L1 of the drill holes.

[0025] In this embodiment, the splitting test is to first make a rock specimen based on the rock sample. During the process of making the rock specimen, stress sensors are pre-buried in the rock specimen. The stress sensors are evenly distributed in the rock specimen. One side of the rock specimen is placed against a fixed rigid body, and the rock specimen is split from the other side of the rock specimen using the splitting head of a splitting machine. By monitoring the stress sensor, multiple sets of data are obtained, each time the splitting head extends to different lengths l, indicating the minimum splitting force F obtained by the rock specimen stress sensor.

[0026] In this embodiment, in step S1, the rock sample with a construction width L2 is determined according to the tensile strength: for hard rock, L2 is 0.5-1.0 m; for medium-hard rock, L2 is 1.0-1.5 m; for soft rock, L2 is 1.5-2 m.

[0027] In this embodiment, in step S2, the excavation group includes a long-arm hook machine and an excavator. After the splitting construction is completed, the long-arm hook machine enters the site to hook and drop the rock split from the whole rock mass, and finally the rock blocks are transported away by the excavator and the transport vehicle.

[0028] In this embodiment, in step S2, splitting construction, excavation construction and excavator insertion are performed sequentially.

[0029] The present invention also includes a construction equipment used in the above construction method, including a drilling and splitting integrated machine, the drilling and splitting integrated machine including a walking mechanism, an articulated seat, a large arm, a rotating support, a frame and a drilling and splitting double-head device,

[0030] An operating table and a rotating platform are installed on the walking mechanism, one end of the boom is fixed to the operating table through an articulated seat, and the other end is connected to the frame through a rotating support. The middle part of the boom is supported on the rotating platform by a hydraulic cylinder, and the boom is driven to rotate around the articulated seat along a vertical plane through the extension and contraction of the hydraulic cylinder. The fixed end of the rotating support is fixed to the boom, and the movable end is connected to the frame. The frame is driven to rotate 360 ​​degrees around the rotation center of the rotating support through the rotating support. The rotation center of the rotating support is in the same straight line as the central axis of the boom. A mounting surface is provided on the frame, and the plane on which the mounting surface is located is perpendicular to the rotation center of the rotating support.

[0031] A linear motion mechanism is installed on the mounting surface of the frame, and the linear motion mechanism includes a slide rail and a plurality of sliders slidably mounted on the slide rail. The slider is provided with a locking mechanism that can lock the relative position of the slider and the slide rail. A drilling and splitting double-head device is installed on each slider, and the drilling and splitting double-head device includes a drill bit, a splitter and a mounting seat. The mounting seat is fixed on the slider, and a group of telescopic cylinders are respectively fixed in the mounting seat with the slide rail as the symmetry axis on the upper and lower sides of the mounting seat. The pushing directions of the two groups of telescopic cylinders are opposite to each other, and the drill bit and the splitter are respectively installed on the movable ends of the two groups of telescopic cylinders.

[0032] In this embodiment, the splitting machine includes a splitting barrel, a splitting head and a splitting oil cylinder. A cavity is provided in the middle of the splitting barrel, and through grooves connected to the cavity are symmetrically opened on both side walls of the splitting barrel. A group of splitting oil cylinder groups is installed in each through groove. Each group of splitting oil cylinder groups includes a plurality of splitting oil cylinders arranged in parallel. A splitting head is installed on the movable end of each group of splitting oil cylinder groups. The splitting heads are arranged along the length direction of the through groove and match the size of the through groove. Driven by the splitting oil cylinder, the splitting head can extend out of the outer wall of the splitting barrel to form a splitting shape or shrink in the through groove of the splitting barrel to form a contracted shape. When the splitting machine is in the contracted shape, the outer diameter of the splitting machine matches the outer diameter of the drill bit. When in the splitting shape, the splitting head extends out of the splitting barrel to form a splitting effect by squeezing the rock mass.

[0033] In this embodiment, the height of the splitting head is 50 cm, the top diameter is 20 cm, and the bottom diameter is 10 cm.

[0034] In this embodiment, the hydraulic cylinder, splitting cylinder, and telescopic cylinder are all connected to the hydraulic system through oil circuits.

[0035] With the above structure, the present invention has the following advantages compared with the existing technology:

[0036] 1. The method of the present invention replans the construction steps of rock foundation pits. Through marking, splitting after drilling, and layer-by-layer excavation, the soil can be split in a predetermined direction by utilizing the form of splitting after drilling, ensuring accurate excavation of the foundation pit, effectively avoiding the phenomenon of over-excavation, and achieving strict control of the excavation range of the foundation pit. At the same time, by determining the maximum interval between adjacent drill holes, on the one hand, work efficiency is greatly improved, and on the other hand, it can ensure that subsequent splitting can achieve the effect of splitting in the predetermined direction;

[0037] 2. The device of the present invention is used for the construction of this method, and the drilling and splitting integrated machine has two working modes, namely drilling and splitting, and the two working modes are realized by only rotating the support to drive the frame to rotate. Through the arrangement of multiple drill bits and corresponding splitters, multiple holes can be drilled at one time, and multiple holes can be split at the same time, which greatly improves the construction efficiency. In the drilling state, the frame rotates until the drill bit is facing the ground, so that the drill bit is used to drill holes; in the splitting state, the frame rotates until the splitter is facing the ground, so that the splitter is used to split. After the splitting is completed, the foundation pit is excavated by using a hook machine to break and an excavator to excavate. It can effectively solve the construction cost and construction safety problems brought by traditional excavation construction methods, and at the same time avoid the safety hazards caused by the disturbance of the rock and soil mass on the slope of the foundation pit. The process is simple and the management is convenient, which solves the problems of complex construction process, high cost and safety hazards of traditional foundation pit excavation methods.

[0038] 3. The integrated drilling and splitting machine leverages rock's high compressive strength and low tensile strength to precisely determine the direction, shape, and required dimensions. It offers high precision, continuous, uninterrupted operation, high efficiency, and low operating and maintenance costs. It is unrestricted by temperature and site conditions, eliminating the need for time-consuming, complex, and expensive safety measures required by other impact operations. While operating, it minimizes environmental impact and is suitable for technically challenging foundation pit excavation projects where blasting is not feasible and high production output is required within tight deadlines. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a top plan view of the foundation pit for construction of the present invention.

[0040] Figure 2 This is a cross-sectional view of the foundation pit for construction of the present invention

[0041] Figure 3 It is a side view of the drilling and splitting machine of the present invention.

[0042] Figure 4 This is a front view of the drilling and splitting machine of the present invention.

[0043] Figure 5 This is a front view of the drill bit of the present invention

[0044] Figure 6 It is a side view of the splitting machine of the present invention.

[0045] Figure 7 It is a schematic cross-sectional view of the splitting machine of the present invention.

[0046] Figure 8 It is a working schematic diagram of the splitting machine of the present invention.

[0047] In the figure, 1. Drilling; 2. Drill bit; 3. Splitting machine; 4. Splitting cylinder; 5. Splitting head; 6. Splitting cylinder; 7. Telescopic cylinder; 8. Oil circuit; 9. Rotating support; 10. Upper arm; 11. Hinge support; 12. Travel mechanism; 13. Frame; 14. Mounting base; 15. Drilling and splitting double-head equipment. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0050] like Figure 1 、 2 As shown, the present invention includes a construction method for impact splitting and precise excavation of a rock foundation pit, which specifically includes the following steps:

[0051] S1: Delimit the scope of the foundation pit:

[0052] Mark the edge of the foundation pit according to the design line. The marking method is to lay out the line and strictly follow the design line of the foundation pit range to avoid any discrepancies with the foundation pit design line.

[0053] Then, within the scope of the foundation pit, multiple circular excavation lines are divided from the center of the foundation pit to the edge of the foundation pit. The interval between adjacent excavation lines is a construction width L2. Construction workers mark the drilling positions along the excavation lines. The interval between the drilling holes is L1. The arrangement of the drilling holes should strictly follow the scope of the excavation lines to avoid misplacement or omission. During construction on sunny days, construction workers mark the drilling positions by spraying lime. During construction on rainy days, construction workers mark the drilling positions by inserting markers.

[0054] Finally, determine the foundation pit soil thickness D for each excavation;

[0055] The specific method for determining the drilling interval L1 and construction width L2 is as follows:

[0056] a. First determine the relationship between the length l of the splitting head and the splitting force F:

[0057] Rock samples were collected at the construction pit location and subjected to strength testing. According to the tensile strength, the rock samples were divided into hard rock (tensile strength ≥ 30 / MPa), medium-hard rock (tensile strength of 10-30 / MPa), and soft rock (tensile strength ≤ 10 / MPa). Rock specimens were prepared based on the rock samples. During the preparation of the rock specimens, stress sensors were pre-embedded in the rock specimens. The stress sensors were evenly distributed within the rock specimens. A splitting test was then conducted on the rock specimens to obtain the relationship between the length l of the splitting head and the splitting force F. The splitting test involved placing one side of the rock specimen against a fixed rigid body and using the splitting head of the splitting machine to split the rock specimen from the other side. By monitoring the stress sensor, multiple sets of data were obtained, indicating the minimum splitting force F obtained by the rock specimen stress sensor each time the splitting head extended to different lengths l. The multiple sets of data were substituted into Origin for nonlinear function fitting to obtain the function f(l) = F.

[0058] b. Determine the relationship between the splitting force F and the working distance L1 between adjacent splitters;

[0059] The minimum working spacing L1 is the sum of the extension lengths l of the splitting heads of adjacent splitters. Then, the empirical coefficient α is defined according to the tensile strength of the rock sample. Here, α = 3 for hard rock, α = 4 for medium-hard rock, and α = 5 for soft rock, resulting in:

[0060] L 1最大 =2αl (1),

[0061] Substituting formula (1) into f(l)=F in S1, we get the functional relationship formula f(L1)=F. When the working spacing L1 of the splitter can meet the strength of the corresponding rock to be split, the maximum value of L1 in the function f(L1)=F is selected as the working spacing of the splitter, which is the interval L1 of the drill holes.

[0062] The rock mass sample of construction width L2 is determined according to the tensile strength:

[0063] For hard rock, L2 is 0.5~1.0m, for medium-hard rock, L2 is 1.0~1.5m, and for soft rock, L2 is 1.5~2m.

[0064] S2: Excavation of foundation pit:

[0065] Excavate from the center of the foundation pit outward in sequence, with each excavation of at least a construction width L2. Specifically, drill holes according to the drilling positions pre-marked on the excavation line, and the drilling depth matches the thickness D of the soil layer excavated each time. After drilling is completed, all holes are inspected and excess rock debris in the holes is cleaned. Then, a splitter is inserted into the hole to split the hole. After the splitting is completed, an excavator is used to excavate the rock layer within the foundation pit excavation line. Repeat the above steps until one layer of foundation pit excavation is completed, and then excavate the next layer of foundation pit soil layer until the entire foundation pit is excavated.

[0066] When the foundation pit excavation reaches the bottom, ensure that the depth of the drill hole matches the final depth of the foundation pit excavation to ensure that there is no over-excavation at the bottom. At the same time, it can save manual excavation and avoid the need for replacement filling, tamping, preloading, pile foundation and other processes after over-excavation, thus saving a lot of project costs.

[0067] In step S2, the excavation group includes a long-arm hook machine and an excavator. After the splitting construction is completed, the long-arm hook machine enters the site to hook up the rock split from the whole rock mass, and finally the rock blocks are transported away by the excavator and the transport vehicle. In this embodiment, the splitting construction, excavation construction and excavation can be carried out in sequence.

[0068] like Figure 3-8 As shown, in this embodiment, construction equipment is used to drill and split the foundation pit. The construction equipment is a drilling and splitting integrated machine, which includes a walking mechanism 12, an articulated seat 11, a large arm 10, a rotating support 9, a frame 13 and a drilling and splitting double-head device 15.

[0069] An operating table and a rotating platform are installed on the walking mechanism 12. The operating table is installed on the rotating platform. One end of the boom 10 is fixed to the operating table through an articulated seat 11, and the other end is connected to the frame 13 through a rotating support 9. The middle part of the boom 10 is supported on the rotating platform by a hydraulic cylinder. The boom 10 is driven to rotate around the articulated seat 11 along a vertical plane through the extension and contraction of the hydraulic cylinder. The rotating support 9 is an electric rotating support. The fixed end of the rotating support 9 is fixed on the boom 10, and the movable end is connected to the frame 13. The frame 13 is driven by the rotating support 9 to rotate 360 ​​degrees around the rotation center of the rotating support. The rotation center of the rotating support 9 is in the same straight line as the central axis of the boom 10. A mounting surface is provided on the frame 13, and the plane where the mounting surface is located is perpendicular to the rotation center of the rotating support 9.

[0070] A linear motion mechanism is installed on the mounting surface of the frame 13, and the linear motion mechanism includes a slide rail and a plurality of sliders slidably mounted on the slide rail. The slider is provided with a locking mechanism that can lock the relative position of the slider and the slide rail. Each slider is installed with a drilling and splitting double-head device 15, and the drilling and splitting double-head device 15 includes a drill bit 2, a splitter 3 and a mounting seat 14. The mounting seat 14 is fixed on the slider, and a group of telescopic cylinders 7 are respectively fixed on the upper and lower sides of the mounting seat 14 with the slide rail as the axis of symmetry. The pushing directions of the two groups of telescopic cylinders 7 are opposite to each other, and the drill bit 2 and the splitter 3 are respectively installed on the movable ends of the two groups of telescopic cylinders 7.

[0071] When the auger 5 is in the working state, the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, and the auger 5 is in the working state, The hydraulic cylinder, the splitting oil cylinder 6 and the telescopic oil cylinder 7 are all connected to the hydraulic system through the oil circuit 8.

[0072] In this embodiment, four drilling and splitting double-head devices 15 arranged side by side are installed on the frame 13, which can perform drilling and splitting on four adjacent positions at the same time, thereby improving construction efficiency.

[0073] The drilling and splitting machine has two working modes: drilling and splitting. The two working modes are achieved by rotating the frame 13 driven by the rotating support 9. In the drilling state, the frame 13 rotates so that the drill bit is facing the ground, thereby using the drill bit 2 for drilling; in the splitting state, the frame 13 rotates so that the splitter 3 is facing the ground, thereby using the splitting machine 3 for splitting.

[0074] Based on actual calculations, this project used traditional hammer excavation, requiring ten 220-type excavators, for a construction period of approximately 50 days. Using the split excavation method, a drilling machine, two integrated drilling and splitting machines, two long-arm hook machines, and four 220-type excavators were used, resulting in a construction period of 30 days. The hammer excavation method cost approximately 800,000 yuan, while the split excavation method cost approximately 340,000 yuan, resulting in a cost savings of approximately 460,000 yuan, representing significant economic benefits.

[0075] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention's description and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A construction method for precise excavation of rock foundation pits by impact splitting, characterized by: The specific steps include: S1. Delimit the scope of foundation pit: Mark the edge of the foundation pit according to the design line, and then divide multiple circular excavation lines from the center of the foundation pit to the edge of the foundation pit. The interval between adjacent excavation lines is one construction width. L 2. Construction workers mark the drilling positions along the excavation line, and the drilling interval is L 1. Finally determine the thickness D of the foundation pit soil layer for each excavation; Determine the drilling interval L 1The method is as follows: a. First determine the length of the splitting head l and splitting force F The relationship between: Collect rock samples at the location of the construction pit and perform strength tests on the rock samples. According to the size of the tensile strength, the rock samples are divided into hard rock, medium hard rock and soft rock. Hard rock refers to rock with a tensile strength of ≥30 / MPa, medium hard rock refers to rock with a tensile strength of 10-30 / MPa, and soft rock refers to rock with a tensile strength of ≤10 / MPa. Then, a splitting test is performed on the rock samples to obtain the length of the splitting head. l and splitting force F The relationship between the obtained multiple sets of data is substituted into Origin for nonlinear function fitting to obtain f( l )= F function; b. Determine the splitting force F Working distance to adjacent splitters L The relationship between 1; Working distance L 1 Minimum extension length of the splitting heads of adjacent splitters l The sum of the two, and then define the empirical coefficient α according to the tensile strength of the rock sample, assuming that hard rock α = 3, medium-hard rock α = 4, and soft rock α = 5, we can get: L 1最大 =2α l ；（1） Substitute equation (1) into function f( l )= F In the equation, we get f( L 1 )= F Functional relationship, in the working distance of the splitter L 1 can meet the requirements of the splitting strength of the corresponding rock, select the function f( L 1 )= F middle L 1 The maximum value is used as the working distance of the splitter L 1. This distance is the interval between drilling holes L 1; S2. Excavation of foundation pit: Excavate from the center of the foundation pit outwards in sequence, excavating at least one construction width each time L 2. Specifically, drill holes according to the drilling positions pre-marked on the excavation line. The drilling depth matches the thickness D of the soil layer excavated each time. After the drilling is completed, clean the excess rock debris in the hole, and then insert a splitter into the hole to split the hole along the excavation line so that the cracks formed by the splitting pass through the adjacent holes along the excavation line. After the splitting is completed, use the excavator group to excavate the rock layer within the foundation pit excavation line; repeat the above steps until one layer of foundation pit excavation is completed, and then excavate the next layer of foundation pit soil layer until the entire foundation pit is excavated.

2. The construction method for precise excavation of rock foundation pits by impact splitting according to claim 1 is characterized in that: The splitting test is specifically as follows: first, a plurality of rock samples are prepared with a tensile strength matching that of the rock sample; during the preparation of the rock samples, stress sensors are pre-embedded in the rock samples, and the stress sensors are evenly distributed in the rock samples; one side of the rock sample is placed against a fixed rigid body, and the splitting head of the splitting machine is used to split the rock sample from the other side of the rock sample; by monitoring the stress sensors, it is determined that the length of the splitting head extending each time is different. l The rock sample stress sensor obtains the minimum splitting force F multiple sets of data.

3. The construction method for precise excavation of rock foundation pits by impact splitting according to claim 1 is characterized in that: In step S1, the construction width L 2. The rock sample is determined according to the tensile strength: when the hard rock L 2 is 0.5~1.0m, for medium hard rock L 2 is 1.0~1.5m, soft rock L 2 is 1.5~2m.

4. The construction method for precise excavation of rock foundation pits by impact splitting according to claim 1 is characterized in that: In step S2, the excavation group includes a long-arm hook machine and an excavator. After the splitting construction is completed, the long-arm hook machine enters the site to hook and drop the rock mass split from the whole rock mass, and finally the rock mass is transported away by the excavator and the transport vehicle.

5. The construction method for precise excavation of rock foundation pits by impact splitting according to claim 4 is characterized in that: In step S2, splitting construction, excavation construction and excavator insertion are carried out in sequence.

6. A construction equipment used in the construction method of impact splitting and precise excavation of rock foundation pits according to any one of claims 1 to 5, characterized in that: It includes a drilling and splitting machine, which includes a traveling mechanism, an articulated seat, a large arm, a rotating support, a frame and a drilling and splitting double-head device. The walking mechanism is equipped with a boom that can rotate along a vertical plane through a hydraulic cylinder. A rotating support is fixed to the end of the boom. The movable end of the rotating support is connected to the frame. The frame is driven by the rotating support to rotate 360 ​​degrees around the rotation center of the rotating support. The rotation center of the rotating support is in the same straight line as the central axis of the boom. The frame is provided with a mounting surface, and the plane on which the mounting surface is located is perpendicular to the rotation center of the rotating support. A linear motion mechanism is installed on the mounting surface of the frame, and the linear motion mechanism includes a slide rail and a plurality of sliders slidably mounted on the slide rail. The slider is provided with a locking mechanism that can lock the relative position of the slider and the slide rail. A drilling and splitting double-head device is installed on each slider, and the drilling and splitting double-head device includes a drill bit, a splitter and a mounting seat. The mounting seat is fixed on the slider, and a group of telescopic cylinders are respectively fixed in the mounting seat with the slide rail as the symmetry axis on the upper and lower sides of the mounting seat. The pushing directions of the two groups of telescopic cylinders are opposite to each other, and the drill bit and the splitter are respectively installed on the movable ends of the two groups of telescopic cylinders.

7. The construction equipment according to claim 6, characterized in that: The splitting machine includes a splitting barrel, a splitting head and a splitting oil cylinder. A cavity is provided in the middle of the splitting barrel, and through grooves connected to the cavity are symmetrically opened on both side walls of the splitting barrel. A group of splitting oil cylinder groups is installed in each through groove. Each group of splitting oil cylinder groups includes a plurality of splitting oil cylinders arranged in parallel. A splitting head is installed on the movable end of each group of splitting oil cylinder groups. The splitting heads are arranged along the length direction of the through groove and match the size of the through groove. Driven by the splitting oil cylinder, the splitting head can extend out of the outer wall of the splitting barrel to form a splitting shape or shrink in the through groove of the splitting barrel to form a contracted shape. When the splitting machine is in the contracted shape, the outer diameter of the splitting machine matches the outer diameter of the drill bit. When in the splitting shape, the splitting head extends out of the splitting barrel to form a splitting effect by squeezing the rock mass.

8. The construction equipment according to claim 7, characterized in that: The height of the splitting head is 50 cm, the top diameter is 20 cm, and the bottom diameter is 10 cm.

9. The construction equipment according to claim 7, characterized in that: The hydraulic cylinder, splitting cylinder and telescopic cylinder are all connected to the hydraulic system through oil circuits.

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