Blasting method suitable for leveling construction site in karst area

Abstract

The invention provides a blasting method suitable for construction site leveling in a karst area, which comprises the following steps: S1, exploring a construction site, and determining a compact rock area, a fractured rock area and a blasting vibration safety distance; s2, geological condition coefficients and attenuation indexes of the compact rock area and the fractured rock area are measured in a small-explosive-quantity trial explosion mode, and the vibration safety speed and the single-hole maximum explosive quantity are calculated; s3, holes are distributed in the compact rock area and the fractured rock area in a shallow hole and deep hole alternating mode, the explosive loading amount of the shallow holes and the deep holes in the compact rock area is 0.7-1 time of the maximum explosive loading amount of a single hole, and the explosive loading amount of the shallow holes and the deep holes in the fractured rock area is 0.5-0.8 time of the maximum explosive loading amount of the single hole; s4, detonation is conducted hole by hole and row by row, the geological condition coefficient and the attenuation index are corrected, and then the drilling and blasting parameters are readjusted according to the corrected geological condition coefficient and attenuation index; and S5, repeating S3 and S4. By means of the method, smooth blasting of the construction site is achieved under the condition that safety is guaranteed.

Description

Technical Field

[0001] This invention specifically relates to a blasting method suitable for leveling construction sites in karst areas, and pertains to the field of site leveling blasting technology. Background Technology

[0002] Karst geology is a product of the long-term interaction between water and soluble rocks, mainly distributed in southwestern my country. Karst areas have complex geological conditions, with solution channels, grooves, caves, and other dissolution fissures. A major challenge in blasting site leveling in karst areas is the inability to determine drilling and blasting parameters. Harmful effects such as vibration, flyrock, and shock waves generated by blasting can injure nearby personnel and buildings. The main reason for this uncertainty is that the geological condition coefficient K and the attenuation index a are prerequisites for determining these parameters, directly affecting the blasting effect and safety of site leveling. In existing technologies, the geological condition coefficient K and the attenuation index a are obtained from the "Table of K and a Values ​​for Different Lithologies in Blasting Areas" and the "Safety Standard for Blasting Vibration." However, this method is only applicable to homogeneous lithology and not to complex karst geology. In karst geology, the distribution of dissolution fissures is highly irregular; rocks at different locations and strata have different K and a values, exhibiting significant variations. Summary of the Invention

[0003] This invention provides a blasting method suitable for leveling construction sites in karst areas, aiming to solve the problem in the prior art where drilling and blasting parameters cannot be determined for leveling construction sites in karst areas.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A blasting method suitable for leveling construction sites in karst areas includes the following steps:

[0006] S1: Explore the construction site to determine the dense rock area, the fractured rock area, and the safe distance R for blasting vibration;

[0007] S2: Determine the geological condition coefficient K and attenuation index a in dense rock areas and fractured rock areas by small-charge test blasting, and calculate the vibration safety velocity V and the maximum charge Qmax per hole to determine the initial drilling and blasting parameters;

[0008] S3: In dense rock areas and fractured rock areas, shallow holes and deep holes are alternately arranged. In dense rock areas, the charge amount of shallow holes and deep holes is 0.7-1 times the maximum charge amount Qmax of a single hole. In fractured rock areas, the charge amount of shallow holes and deep holes is 0.5-0.8 times the maximum charge amount Qmax of a single hole.

[0009] S4: Detonate hole by hole and row by row, and correct the geological condition coefficient K and attenuation index a. Then, readjust the drilling and blasting parameters according to the corrected geological condition coefficient K and attenuation index a.

[0010] S5: Repeat S3 and S4.

[0011] Further improvements to the technical solution: shallow hole depth of 2-4m, deep hole depth of 5-8m.

[0012] Further improve the technical solution: small-scale test explosion includes drilling, charging and detonation, and then the geological condition coefficient K and attenuation index a are determined by seismic detector, displacement sensor and data analysis module.

[0013] Further improvements to the technical solution: the inter-hole delay detonation time is 30-50 milliseconds, and the inter-row delay detonation time is 100-130 milliseconds.

[0014] Further improve the technical solution: The formula for calculating the vibration safety velocity V is: g is the acceleration due to gravity.

[0015] Further improve the technical solution: Maximum charge Q per hole max The calculation formula is: .

[0016] Further improvements to the technical solution: shallow holes adopt a continuous coupled charging structure, while deep holes adopt an air-spaced segmented charging structure.

[0017] Further improve the technical solution: Pre-install a buffer rock wall around the construction site.

[0018] After implementing the above technical solution, compared with the prior art, the present invention can produce the following beneficial effects:

[0019] 1. Based on the irregular distribution of dissolution fissures in karst areas, this invention optimizes drilling and blasting parameters by simultaneously modifying the geological condition coefficient K and attenuation index a during blasting. This achieves leveling blasting of construction sites in karst areas while ensuring safe blasting.

[0020] 2. This invention uses a precise geological model as input, plans the macroscopic path of energy release through step blasting and "lateral non-escape" technology, and then uses electronic detonator micro-delay initiation technology to finely deconstruct and recombine the explosion energy in time and space, quantifying and suppressing harmful effects such as vibration and flyrock within safety standards.

[0021] 3. By carefully designing the detonation sequence of the front and rear rows of blast holes, this invention not only reduces the clamping effect of the rock, allowing the rock to be fully broken and loosened, but also ensures that the amount of explosive at any given moment is small enough, thereby reducing the particle vibration velocity below the safety threshold.

[0022] 4. This invention formulates corresponding drilling and blasting parameters according to the lithology of different regions, and reduces the total amount of explosives used by combining shallow hole drilling and blasting with deep hole drilling and blasting, thus effectively reducing blasting costs. Attached Figure Description

[0023] Appendix Figure 1 The image shown is a plan of the proposed construction site.

[0024] Appendix Figure 2 The diagram shown is a plan view of the blasting holes.

[0025] Appendix Figure 3 The diagram shown is a schematic of deep-hole bench controlled blasting.

[0026] Appendix Figure 4 The diagram shown is a schematic of the vertical borehole arrangement.

[0027] Appendix Figure 5 The diagram shown is a schematic of the arrangement of inclined blast holes.

[0028] Appendix Figure 6 The diagram shown is a flowchart of the present invention. Detailed Implementation

[0029] The construction site leveling blasting method of the present invention includes the following steps:

[0030] S1: Explore the construction site to determine the dense rock area, the fractured rock area, and the safe distance R for blasting vibration.

[0031] See attached document Figure 1 In this embodiment, the construction project involves building sorghum warehouses #4 and #5 on a karst site. Initially, the site needs to be leveled using blasting. The project site is located in a karst valley topography, with alternating gentle slopes and karst troughs. The site is situated on the northwest side of the valley, surrounded by mountains on the north, east, and south sides, and a valley on the west, generally resembling a basket opening to the west. The minimum distance between the project site and the settlement area is approximately 240 meters, and the vibrations and flying rocks generated by blasting could potentially damage the settlement. Blindly blasting could easily lead to uncontrolled explosive energy due to unfavorable geological features such as caves and fissures, causing flying rocks, shock waves, or excessive vibrations. Therefore, the construction method adopts a "survey first, design later" approach. Through on-site geological surveys and statistical analysis of rock mass structure surfaces, the occurrence of rock strata, the development and spatial distribution of joints and fissures (such as J1 and J2 groups), and the potential location of karst formations are determined. Based on this, a three-dimensional geological model is constructed, including the complete rock mass, structurally weak surfaces, and karst cavities. This model is the fundamental basis for the design of all subsequent parameters. It determines how the blast holes should avoid major karst caves and how the explosive energy should conform to or cut the joint surfaces, thereby achieving predictability of the blasting effect.

[0032] To ensure the safety of people and buildings in the settlement area, the location, size, and filling condition of the dissolution fissures were first determined using a combination of intensified geological drilling and borehole photography within the construction site area. Based on the exploration results, the blasting area was divided into dense rock areas and fissured rock areas. Then, the safe blasting vibration distance R was determined based on the distance from the construction site to the nearest sorghum warehouse, and the formula was applied... Calculate the vibration safety velocity V. Where g is the acceleration due to gravity. In this embodiment, the blasting vibration safety distance R is set to 220m.

[0033] S2: The geological condition coefficient K and attenuation index a of dense rock area and fractured rock area are determined by small-charge test blasting, and the vibration safety velocity V and the maximum charge amount Qmax of a single hole are calculated to determine the initial drilling and blasting parameters.

[0034] Small-scale test blasting includes drilling, charging, and detonation. In this embodiment, the borehole diameter is 40mm and the depth is 4m. Small-diameter emulsion explosive cartridges are continuously loaded, and the charge amount is strictly controlled. Then, the geological condition coefficient K and attenuation index a are determined using a seismic detector, displacement sensor, and data analysis module. The purpose of the small-scale test blasting is to determine the lithology of the detonation area in the field, providing a realistic reference for the borehole drilling and blasting parameters.

[0035] Specifically, tools such as total stations, levels, measuring ropes, and steel tape measures are used to measure the concentration and looseness of the blast pile, and to determine whether there is "slag compaction" or "backward pulling". The proportion of large rocks is statistically analyzed as a basis for adjusting the unit explosive consumption and hole layout parameters. It is checked whether there is a root sill, and the reason is whether the hole depth is insufficient or the resistance line is too large. After the blasting, the surveyors promptly scan and measure the formed slope to check the slope flatness and stability, providing a basis for smooth blasting or mechanical slope repair.

[0036] Vibration monitoring points are set up near protected objects (such as residential buildings and national highways). Digital blasting vibration monitoring instruments are used to record the triaxial particle vibration velocity and dominant frequency. The measured vibration data V is then compared with the predicted value using the Sadovsky formula. If the vibration value approaches or exceeds the safety allowable standard, the maximum charge Q per hole must be reduced in the next blast. max Given the safe distance R for blasting vibration, the safe vibration velocity V, the geological condition coefficient K, and the attenuation index a, the Sadovsky formula can be used to... The maximum charge Q per orifice can be calculated. max .

[0037] S3: In dense rock areas and fractured rock areas, shallow holes and deep holes are alternately arranged. In dense rock areas, the charge amount of shallow holes and deep holes is 0.7-1 times the maximum charge amount Qmax of a single hole. In fractured rock areas, the charge amount of shallow holes and deep holes is 0.5-0.8 times the maximum charge amount Qmax of a single hole.

[0038] See attached document Figure 2 First, verify the topography and geological changes of the blasting area, especially the development of karst caves and fissures, and confirm the excavation boundaries. When drilling, avoid identified obvious karst caves and large fissures. If avoidance is impossible, record them and treat the holes specially during subsequent charging. This invention primarily uses vertical holes, with inclined holes used locally to optimize blasting effects. Before drilling, check the stability of the drilling rig and ensure the drill rod is aligned with the center of the hole. During drilling, observe changes in rock powder, record the drilling speed, and make a preliminary assessment of whether the geological conditions match the design.

[0039] See attached document Figure 3 After constructing the geological model, "deep-hole bench controlled blasting" was adopted as the basic method. Its fundamental principle lies in creating a good free face and strictly controlling the direction of the minimum resistance line (W1). By excavating in a "top-down, north-to-south" sequence, the free face of each bench was artificially guided to the unobstructed area to the north. This is equivalent to indicating the direction for the work done by the explosive stress wave and the expansion of the explosive gas, so that the energy can be concentrated on the crushing and displacement of the rock, rather than spreading randomly in all directions.

[0040] After knowing the maximum charge Q max In this case, the shallow hole drilling and blasting parameters are determined as follows:

[0041] (1) Drilling diameter d: d = 40 mm;

[0042] (2) Shallow hole arrangement: plum blossom pattern;

[0043] (3) Chassis resistance line W1: W1 = (0.4~1.0)H;

[0044] (4) Excavation depth H: 1.5~4.0;

[0045] (5) Hole spacing a: a = (1.0~2.0)W1;

[0046] (6) Row spacing b: b = 0.866a (using equilateral triangle hole arrangement);

[0047] (7) Vertical hole drilling length L: L = (H + Δh);

[0048] (8) Ultra-deep Δh: Δh = (0.1~0.15)H;

[0049] (9) Unit explosive consumption q: Using Φ32 emulsion explosive, q=0.42 kg / m 3 ;

[0050] (10) Charge length L1: L1=Q / qx qx: linear density of charge in the borehole qx=1.0kg / m;

[0051] (11) Filling length L2: L2 = L - L1 should satisfy L2 ≥ 1.0W1;

[0052] (12) Loading method: continuous coupling loading.

[0053] The parameters for deep hole drilling and blasting are determined as follows:

[0054] (1) Drilling diameter D: D = 90 mm;

[0055] (2) Layer height H: Selected according to site conditions (5-6m);

[0056] (3) Deep hole layout: plum blossom pattern;

[0057] (4) Chassis resistance line W1: W1 = (25~35)D;

[0058] (5) Ultra-deep Δh: Δh = (0.12~0.25)H, take 0.50m;

[0059] (6) Vertical hole drilling length L: L = (H + Δh);

[0060] (7) Hole spacing a: a = mW1 (m ≥ 1.0);

[0061] (8) Row spacing b: b = 0.866a (using equilateral triangle hole arrangement);

[0062] (9) Unit explosive consumption q: q = 0.3 kg / m 3 ;

[0063] (10) Charge length L1: L1=Q / qx qx: linear density of charge in the borehole qx=3.6kg / m;

[0064] (11) Filling length L2: L2 = L - L1 should satisfy L2 ≥ 1.0W1;

[0065] (12) Loading method: air-gap segmented loading.

[0066] The main function of shallow-hole drilling and blasting is to increase the fragmentation of the upper rock mass, while the main function of deep-hole drilling and blasting is to split the lower rock mass, forming free surfaces. Combining shallow-hole drilling and blasting with deep-hole drilling and blasting can improve the efficiency of blasting and leveling in karst sites and reduce the total amount of explosives used.

[0067] To achieve more precise control, the "no lateral escape" blasting technology concept was introduced. When facing sensitive targets such as the G352 National Highway to the south, a 2.5-3.0m wide rock wall was reserved at the southern boundary, effectively increasing the minimum resistance line towards the protected object. According to the principles of blasting mechanics, the main direction of rock fragmentation and throwing is the direction of the minimum resistance line. Therefore, this rock wall forms a natural barrier, physically preventing the escape of blast energy and flying rocks to the south, ensuring the absolute safety of the national highway.

[0068] S4: Detonate hole by hole and row by row, and correct the geological condition coefficient K and attenuation index a. Then, readjust the drilling and blasting parameters according to the corrected geological condition coefficient K and attenuation index a.

[0069] See attached document Figure 4 and attached Figure 5 According to the Sadovsky formula, the intensity of blasting vibration is positively correlated with the cube root of the single-stage charge Q. To ensure blasting effectiveness and safety on flat construction sites, for dense rock areas, the charge amount in shallow and deep holes is 0.7-1 times the maximum single-hole charge Qmax. For fractured rock areas, the charge amount in shallow and deep holes is 0.5-0.8 times the maximum single-hole charge Qmax.

[0070] Furthermore, this invention employs electronic digital detonators to precisely determine the total charge ΣQ of a single detonation on a time scale, achieving "hole-by-hole detonation." Each borehole or several boreholes constitute a detonation segment, and the charge Q of each segment is strictly controlled within the safe allowable value calculated using a formula (e.g., 26.5 kg). Through precise delays of tens of milliseconds between boreholes and between rows, it ensures that the preceding and following boreholes create new free surfaces for subsequent boreholes, while also ensuring that the charge at any given moment is sufficiently small, thereby reducing the particle vibration velocity to below the safety threshold of the protected object (e.g., residential buildings).

[0071] Flying rocks are mainly caused by insufficient resistance, poor sealing, or energy escaping from weak surfaces. By strictly adhering to the design parameters for borehole layout, ensuring the measured value of the minimum resistance line W1 matches the design value, guaranteeing sufficient sealing length (L2≥1.0W1), and using rock cuttings for dense sealing, the premature escape of explosive gases is prevented. Pre-installing rock walls in sensitive directions fundamentally cuts off the flying rock path. The theoretical basis is the empirical formula for flying rock distance R=KD. By controlling the borehole diameter D and taking comprehensive measures, the value of K is kept within a safe range, ensuring the flying rock distance is much smaller than the warning radius. Shock waves are caused by the expansion and compression of air by explosive gases. Through effective sealing, the energy is fully confined within the borehole for rock breaking, while avoiding exposed blasting, thus reducing the intensity of the shock wave at its source.

[0072] This invention employs digital electronic detonators for sequential, row-by-row micro-delay detonation. The inter-hole detonation delay is 30-50 milliseconds, and the inter-row detonation delay is 100-130 milliseconds. To prevent misfires and missed shots, a single detonation should not exceed four rows. The principle of this high-precision electronic digital detonator detonation system surpasses the fixed delay range of traditional electric detonators or detonating cord detonators. It allows for individual setting of the detonation time for each borehole, enabling flexible "hole-by-hole detonation" or "row-by-row detonation." By carefully designing the detonation sequence (e.g., 17ms for the first row, 42ms for the second row, and 85ms for the third row), the detonation of the first row of boreholes ensures that the rock has just begun to move and form a new free surface, allowing the subsequent rows of boreholes to detonate immediately. This fully utilizes the new free surface, reducing the rock's clamping effect and ensuring thorough rock fragmentation and loosening. This invention uses a precise geological model as input, plans the macroscopic path of energy release through step blasting and "lateral non-escape" technology, and then uses electronic detonator micro-delay initiation technology to finely deconstruct and recombine the explosion energy in time and space, quantifying and suppressing harmful effects such as vibration and flyrock within safety standards. Finally, through rigorous construction organization and safety precautions, the design scheme is transformed into a realistic and controllable blasting operation.

[0073] During detonation, the geological condition coefficient K and attenuation index a of the blast zone are corrected using seismic detectors, displacement sensors, and data analysis modules, providing a realistic reference for subsequent drilling and blasting. Then, based on the corrected geological condition coefficient K, attenuation index a, and post-blast effects, the drilling and blasting parameters for deep and shallow holes are readjusted to ensure safe blasting in both dense and fractured rock areas, preventing vibrations, flyrock, and shock waves generated by the blast from damaging nearby buildings.

[0074] S5: Repeat S3 and S4.

[0075] See attached document Figure 6 After detonation, the post-blast effect is assessed. If the blasting effect and safety meet design requirements, the drilling and blasting parameters are recalculated, the explosives are loaded, and detonation is repeated according to the previous drilling and blasting parameters. If the blasting effect and safety do not meet design requirements, the geological condition coefficient K and attenuation index a are adjusted. Based on the adjusted geological condition coefficient K, attenuation index a, and post-blast effect, the drilling and blasting parameters for deep and shallow holes are readjusted, and then the drilling, explosives are loaded, and detonation is repeated.

[0076] To improve operational efficiency, two working faces can be set up in the blasting zone. One face can be used for blasting operations, while the other face can be used for mechanical shoveling and transportation. The two working faces can be operated alternately. Alternatively, a blasting method that gradually advances from the edge to the center can be adopted, which facilitates mechanical shoveling and transportation operations.

[0077] It is worth noting that the content not described in detail in the above embodiments is prior art. It is also worth noting that any additions, subtractions, substitutions, and improvements made by those skilled in the art based on the structure and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A blasting method suitable for leveling construction sites in karst areas, characterized in that: Includes the following steps: S1: Explore the construction site to determine the dense rock area, the fractured rock area, and the safe distance R for blasting vibration; S2: Determine the geological condition coefficient K and attenuation index a in dense rock and fractured rock regions through small-charge test blasts, and calculate the vibration safety velocity V and the maximum charge Q per hole. max Determine the initial drilling and blasting parameters; S3: In dense rock and fractured rock regions, shallow and deep holes are alternated. In dense rock regions, the charge amount in shallow and deep holes is the maximum charge amount Q per hole. max The charge amount in shallow and deep holes within the fractured rock region is 0.7-1 times the maximum charge amount Q per hole. max 0.5-0.8 times; S4: Detonate hole by hole and row by row, and correct the geological condition coefficient K and attenuation index a. Then, readjust the drilling and blasting parameters according to the corrected geological condition coefficient K and attenuation index a. S5: Repeat S3 and S4.

2. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: Shallow holes have a depth of 2-4m, and deep holes have a depth of 5-8m.

3. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: Small-scale test explosions include drilling, charging, and detonation, followed by the determination of the geological condition coefficient K and attenuation index a using seismic detectors, displacement sensors, and data analysis modules.

4. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: The inter-hole delay detonation time is 30-50 milliseconds, and the inter-row delay detonation time is 100-130 milliseconds.

5. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: The formula for calculating the vibration safety velocity V is: g is the acceleration due to gravity.

6. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: Maximum charge per orifice Q max The calculation formula is: .

7. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: Shallow holes employ a continuous coupled charge structure, while deep holes employ an air-spaced segmented charge structure.

8. The blasting method for leveling construction sites in karst areas as described in claim 1, characterized in that: A buffer rock wall is pre-installed around the construction site.

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