A method for excavating marine underground engineering based on time-controlled blasting

Abstract

The present invention provides a method for excavating an underground marine project based on sequential controlled blasting, comprising the following steps: arranging the first blasting hole and the last blasting hole in the following manner: 1) arranging the first blasting hole and the last blasting hole alternately; 2) arranging them in the order of first blasting hole, last blasting hole and first blasting hole, and repeating the arrangement; selecting the arrangement mode, setting the blasting parameters based on the rock properties of the working face to be blasted; the blasting parameters include the charge density of the blasthole line, the uncoupling coefficient in the charge structure, the detonation time difference and the distance between the blasting holes; collecting the half-hole rate and the large block rate after blasting to optimize the charge density of the blasthole line and the distance between the blasting holes. By using the method of sequential controlled blasting, the amount of explosives required for blasting is effectively reduced, while the blasting efficiency is improved, and the consumption of materials and manpower during the construction process is reduced, thereby saving costs. By optimizing the number of blasting holes and charge parameters, the construction quality and safety are guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of marine underground construction, and in particular to a marine underground engineering excavation method based on time-sequence controlled blasting. Background Art

[0002] In the process of excavation of marine underground engineering, the step blasting method is usually used. Although step blasting can improve the economic efficiency of excavation, it will inevitably produce strong impact and disturbance on the rock mass near the excavation area while forming through cracks between the blastholes, and cause cumulative damage to the rock mass in the middle and far areas. These two contradictory and unified aspects always exist in rock blasting excavation engineering, and are also problems that blasting engineers need to face in their work for a long time.

[0003] In order to achieve the formation of smooth through cracks between blastholes after rock blasting and excavation, while controlling the degree of damage to the retained rock mass, a method based on time-controlled blasting is used to increase the distance between adjacent blastholes, reduce the number of drill holes, reduce the degree of rock fragmentation around the blastholes, inhibit the formation of seepage channels in the surrounding rock that connect the underground space with the external ocean, reduce the risk of sudden water inrush in marine underground projects, save labor and machine loss costs, and improve the economic benefits of engineering projects. Therefore, the study of time-controlled blasting has practical engineering significance. Summary of the invention

[0004] The present invention proposes a marine underground engineering excavation method based on time-controlled blasting to solve the technical problem that the existing step blasting method will form through cracks between blastholes and produce strong impact disturbance on the rock mass in the vicinity of the excavation, making it difficult to confirm the blasting parameters.

[0005] In order to solve the above technical problems, the present invention provides a method for excavating an underground marine engineering project based on time-controlled blasting, comprising the following steps:

[0006] Step S1: Arrange the first blast hole and the second blast hole in the following manner:

[0007] 1) Alternately arranging the first blasting holes and the second blasting holes;

[0008] 2) Arrange in the order of first blast hole - second blast hole - first blast hole, and repeat the arrangement;

[0009] Step S2: Selecting a layout mode, and setting blasting parameters based on the rock properties of the working face to be blasted; the blasting parameters include charge density of the blasthole line, uncoupling coefficient in the charge structure, detonation time difference and distance between blastholes;

[0010] Step S3: Collect the half-hole rate and large block rate after blasting to optimize the charge density of the blasthole line and the distance between blastholes.

[0011] Preferably, when the first arrangement is selected in step S2, the spacing between the first blast hole and the second blast hole is calculated by the following formula:

[0012] ;

[0013] In the formula, is the critical compressive strength of rock, It represents the maximum tangential stress at the point C on the wall of the later explosion hole B that is closest to the earlier explosion hole A; represents the lateral stress coefficient; P0 represents the initial pressure acting on the hole wall after the blasting of the first blast hole; R A Indicates the radius of the first blast hole A; R B represents the radius of the post-explosion hole B; represents the Poisson's ratio of the rock mass; L represents the distance between the first blast hole and the second blast hole.

[0014] Preferably, when the second arrangement is selected in step S2, the spacing between the first blast hole and the second blast hole is calculated by the following formula:

[0015] ;

[0016] In the formula, is the critical compressive strength of rock, It represents the maximum tangential stress at the point C on the wall of the later explosion hole B that is closest to the earlier explosion hole A; represents the lateral stress coefficient; P0 represents the initial pressure acting on the hole wall after the blasting of the first blast hole; R A Indicates the radius of the first blast hole A; R B represents the radius of the post-explosion hole B; represents the Poisson's ratio of the rock mass; L represents the distance between the first blast hole and the last blast hole;

[0017] The spacing between adjacent post-blast holes is calculated using the following formula:

[0018] ;

[0019] In the formula, is a fixed value of rock fracture toughness related to rock properties; represents the crack tip strength factor; Represents the static pressure in the blast hole during sequential controlled blasting; R B represents the radius of the post-explosion hole B; represents charge density; D represents explosive detonation velocity; k1 represents uncoupling coefficient; k2 represents charge coefficient; Indicates the spacing between post-blast holes.

[0020] Preferably, in step S1, a V-grooving operation or a shaped charge treatment is performed on the first blasthole; or, in step S1, a V-grooving operation or a shaped charge treatment is performed on the first blasthole and the second blasthole.

[0021] Preferably, after the V-grooving operation or the shaped charge treatment, the spacing between two adjacent post-blast holes is calculated by the following formula:

[0022] ;

[0023] ;

[0024] ;

[0025] is a fixed value of rock fracture toughness related to rock properties; represents the crack tip strength factor; Indicates the static pressure in the blast hole during sequential controlled blasting; Indicates the instantaneous pressure of the explosive gas when the shaped charge explodes; R B represents the radius of the post-explosion hole B; represents charge density; D represents explosive detonation velocity; k1 represents uncoupling coefficient; k2 represents charge coefficient; Indicates the spacing between post-blast holes; It indicates the pressure coefficient of the blast hole in the sequential blasting; represents the blasting pressure coefficient; PK represents the critical pressure; It indicates the volume of gas generated by blasting of shaped charge; It represents the volume of explosives in the blast hole; a is the isentropic index; b is the adiabatic index.

[0026] Preferably, step S3 is optimized by the following formula:

[0027] ;

[0028] In the formula, Indicates the optimized line charge density; , and represents the error coefficient; Indicates the density of the line charge used in blasting; It indicates the half-hole rate of the blasting at that time; is the semi-porosity required for each lithology; is the rate of large blocks in the current blasting; Indicates the block diameter corresponding to the lower envelope The block rate; Indicates the block diameter corresponding to the upper envelope The block rate.

[0029] Preferably, in step S2, the arrangement mode is selected by the following method:

[0030] Step S21: Experimenting with all arrangements;

[0031] Step S22: selecting excavation cost per meter, pyrotechnic cost per meter, half-hole ratio after blasting and absolute value of flatness after blasting as indicators, and establishing evaluation rules including four levels of excellent, good, medium and unsatisfactory;

[0032] Step S23: Based on the experimental results and the evaluation rules, after calculating the membership matrix and the weight matrix, a comprehensive score is calculated, and the arrangement method with the highest comprehensive score is selected to proceed to the subsequent steps.

[0033] Preferably, the detonation time difference between the first blast hole and the second blast hole is Set to: =25ms~80ms.

[0034] Preferably, the uncoupling coefficient in the charge structure is set to 2-4.

[0035] The beneficial effects of the present invention include at least: the present invention can effectively reduce the vibration and noise generated during blasting by detonating in stages and batches through the method of sequentially controlling blasting; reduce the propagation of stress waves, reduce the damage to surrounding existing structures (such as submarine tunnels, platform foundations, etc.), and protect the safety of the project; effectively reduce the amount of explosives required for blasting, while improving blasting efficiency, reducing the consumption of materials and manpower during construction, and thus saving costs. At the same time, the present invention ensures construction quality and safety by optimizing the number of blasting holes and charging parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of a method flow of an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of a blasthole detonation network arranged in the first manner of an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of the spacing of blastholes arranged in the first manner of an embodiment of the present invention;

[0039] Figure 4 The figure is a schematic diagram of the arrangement after the explosion hole is processed according to the embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0041] Example 1

[0042] like Figure 1 As shown, an embodiment of the present invention provides a method for excavating an underground marine engineering project based on time-controlled blasting, comprising the following steps:

[0043] Step S1: Arrange the first blast hole and the second blast hole in the following manner:

[0044] 1) Alternately arrange the first blasting holes and the last blasting holes; specifically, divide the pre-splitting holes in the same row into first blasting holes and last blasting holes, set the first hole as the last blasting hole, the second hole as the first blasting hole, the third hole as the last blasting hole, the fourth hole as the first blasting hole, the fifth hole as the last blasting hole, the sixth hole as the first blasting hole, and so on, with two blasting holes forming a group.

[0045] 2) Arrange in the order of first blasting hole-later blasting hole-first blasting hole, and repeat the arrangement; specifically, divide the pre-splitting holes in the same row into first blasting holes and later blasting holes, set the first hole as the later blasting hole, the second hole as the first blasting hole, the third hole as the later blasting hole, the fourth hole as the later blasting hole, the fifth hole as the first blasting hole, the sixth hole as the later blasting hole, and so on, with three blasting holes forming a group.

[0046] The sequential controlled blasting method mainly utilizes the stress wave of the explosion of the first blast hole to produce a tensile effect on the wall of the second blast hole, so that the rock around the second blast hole is tensilely fractured in a specific direction. When the stress wave of the explosion generated by the first blast hole propagates to the second blast hole, the stress wave will produce a reflected tensile effect at the boundary of the hole wall. Since the rock is a material that is resistant to compression but not to tension, and the stress wave reflected tensile effect on the explosion surface of the hole wall is the largest, when the tensile stress on the hole wall rock is greater than the dynamic tensile strength of the rock, initial cracks will be generated first along the direction of the blast hole line, and the cracks will continue to expand forward after the second blast hole is detonated.

[0047] Step S2: Select the layout mode and set the blasting parameters based on the rock properties of the working face to be blasted; the blasting parameters include the charge density of the blasthole line, the uncoupling coefficient in the charge structure, the detonation time difference and the distance between the blastholes.

[0048] Specifically, the steps include:

[0049] Step 1: Divide the blasting face area into zones according to rock properties.

[0050] Step 2: According to the size of the blasting face area and the previous blasting data, and based on the rock properties in step 1, preliminarily determine the hole grid parameters of the blasting face. The following is the determination of the important parameters in this method.

[0051] Charge density at blasthole line d , where d is the diameter of the blasthole; L is the distance between blastholes; k is the rock coefficient; and the uncoupling coefficient in the charge structure should be 2~4.

[0052] Set the detonation time difference between the first blast hole and the last blast hole It is necessary to detonate the post-blasthole when the tangential tensile stress on the rock mass of the hole wall along the blasthole line is the maximum. If the post-blasthole is detonated too early, the maximum concentrated tensile stress effect cannot be achieved. If the post-blasthole is detonated too late, the stress field of the post-blasthole and the first blasthole cannot be superimposed on each other, which is equivalent to two single-hole detonations without forming a whole. = in The time when the maximum concentrated tensile stress is generated after the explosion. Time for pre-cracks to form for post-blasting.

[0053] The period from the completion of the explosion reaction of all the explosive columns to the dissipation of the explosion gas in pre-splitting deep hole blasting can last for 20ms~120ms. Under normal conditions, in open-air deep hole blasting, it takes about 1.8s~2.2s to complete the entire blasting process. In hard rock, when the chassis resistance line is less than 10m, it takes about 10ms~25ms from detonation to the appearance of cracks on the step slope. Under normal circumstances, large cracks appear on the top of the step, which takes about 80ms~150ms. After that, the explosive gas dissipates and the rock mass breaks and is thrown out. Therefore, in the embodiment of the present invention, the detonation time difference between the first blast hole and the second blast hole is selected The time range is: =25ms~80ms.

[0054] Regarding the setting of the blasthole spacing, when the first arrangement method is selected, it only involves the calculation of the spacing between successive blastholes, and the method is as follows.

[0055] After the blast hole is detonated, the radial stress and tangential stress at any point P in the rock mass are caused by the explosion stress wave during its propagation in the medium, which can be calculated as follows.

[0056] ;

[0057] ;

[0058] ;

[0059] ;

[0060] Where: , are the radial stress and tangential stress at any point P, MPa; P0 is the initial pressure acting on the hole wall, MPa; L AP is the distance from any point P to the center of the first blast hole A, mm; R A is the radius of the first blast hole A, mm; is the stress wave attenuation coefficient; is the lateral stress coefficient; is the Poisson's ratio of the rock mass.

[0061] In the sequential controlled blasting, the first blast hole A is detonated first, and the second blast hole B is detonated after a short delay. This detonation method will cause the explosion stress wave to propagate to the vicinity of the second blast hole B after the first blast hole A is detonated. The explosion stress wave is reflected at the wall of the second blast hole B. The superposition of the reflected wave and the stress wave reduces the pressure inside the second blast hole B, and then turns into a tensile stress state, causing the stress concentration.

[0062] At this time, when the stress wave propagates to point C near the post-explosion hole B, the stress state at point C is:

[0063] ;

[0064] In the formula, , and Respectively represent the radial stress, tangential stress and shear stress at point C near the post-explosion hole B, MPa; R B is the radius of the post-explosion hole B, mm; L BC is the distance from point C to the center of the back blast hole B, mm; It is the angle between the line from point C to the center of the first blast hole A and the center line of the first blast hole A and the second blast hole B.

[0065] When the stress wave propagates to the wall of post-explosion hole B, L BC =R B , then m=1, and the boundary conditions are brought into the calculation to obtain:

[0066] ;

[0067] In the above formula right To perform the derivation, let , solve , and then get The maximum and minimum values ​​of :

[0068] ;

[0069] In the direction of the centerline of the blastholes, the tangential stress is the largest, and the tangential stress decreases as the distance between the centers of the successive blastholes increases. According to fracture mechanics, cracks between rock masses will expand along the direction of the maximum circumferential tensile stress. From the above formula, we can see that when At that time, that is, in the direction of the centerline connecting the AB holes, the tangential tensile stress on the rear hole B is the largest, so the crack will develop along this direction. The maximum crack expansion in the direction of the first and second holes, that is, the spacing L between the first and second holes, is constrained and calculated by the following formula:

[0070] ;

[0071] In the formula, is the critical compressive strength of rock.

[0072] When the second arrangement is selected, the spacing between the first and second blastholes is calculated in the same way as the first arrangement, while the spacing between adjacent second blastholes, i.e. the spacing between the first and second blastholes, is The calculation is performed by the following method.

[0073] Initial cracks appeared in the post-blast hole B. After the post-blast hole B was detonated again, due to the existence of the initial cracks, the explosion stress wave would first act on the initial cracks. Type I opening cracks were generated between the successive blast holes under the action of tensile stress. According to the crack propagation theory, if the crack tip strength factor is greater than the critical fracture value of the rock mass, the crack will continue to propagate.

[0074] ;

[0075] ;

[0076] Where: is the crack tip strength factor; is the crack extension length, i.e., the distance between adjacent post-blast holes; P1 is the static pressure in the blast hole during sequential controlled blasting; is the charge density; D is the detonation velocity of the explosive; k1 is the uncoupling coefficient; k2 is the charge coefficient.

[0077] when Greater than the fracture toughness of the rock mass , the crack continues to expand. As the crack continues to expand, the crack tip intensity factor will continue to decrease. Finally, when the crack tip intensity factor Less than the fracture toughness of the rock mass , the crack stops expanding. So when the crack tip strength factor Equal to the fracture toughness of the rock mass , the crack reaches its maximum length The maximum crack extension length between adjacent post-blasting holes in sequential controlled blasting, that is, the maximum arrangement spacing between adjacent post-blasting holes, can be obtained according to the following formula.

[0078] ;

[0079] Where: is a fixed value of rock fracture toughness related to rock properties.

[0080] Step 3: Arrange the hole positions and drill holes on the blasting face according to the specific conditions on site and the hole network parameters in step 2, and strictly check whether the parameters are met after the drilling is completed.

[0081] Step 4: After the drilling is completed, charge filling is carried out according to the line charge density and charge structure in step 2. The pre-splitting holes are connected according to the first blasting holes and the second blasting holes respectively. A detonating cord is used to connect the first blasting hole of this pre-splitting blasting, and another detonating cord is used to connect the second blasting hole of this pre-splitting blasting. Detonation is carried out according to the set detonation time difference. Taking the first arrangement as an example, the schematic diagram of the blasthole detonation network is as follows Figure 2 and Figure 3 shown.

[0082] Step S3: Collect the half-hole rate and large block rate after blasting to optimize the charge density of the blasthole line and the distance between blast holes.

[0083] After the blasting is completed, after the slag removal work is completed, the data of the half-hole rate, root rate, flatness and large block rate of this blasting are collected and sorted out. The relevant hole network parameters are optimized and adjusted before the next blasting operation in the similar lithology area is carried out. The data is collected again to continuously optimize the hole network parameters.

[0084] Specifically, half porosity It refers to the length ratio of the blasthole traces left on the slope wall after smooth blasting or pre-splitting blasting. The effect of pre-splitting blasting on slopes of different lithologies can be divided into: hard rock, ≥80%, medium hard rock, ≥50%, soft rock, ≥20%.

[0085] The calculation formula of semi-porosity is:

[0086] ;

[0087] in is the total length of the remaining blastholes after blasting, Total length of blast holes.

[0088] The large block rate is an important indicator to measure the blasting quality. It refers to the proportion of rock blocks that exceed a certain size requirement produced during the blasting process.

[0089] By volume method The large block rate is calculated:

[0090] ;

[0091] in The diameter of the rock block after blasting is larger than the diameter The sum of the rock volumes, V is the total volume of the blasting.

[0092] If the half-porosity is too low, it means the blasting effect is not good. If the bulk rate is too large or too low (outside a certain range), it means the blasting effect is not good. ≥80%, medium hard rock, ≥50%, soft rock, ≥20%, the half porosity needs The large block rate must meet the actual project requirements. In actual projects, the rock block diameter grading curve produced by blasting needs to be between the upper envelope and the lower envelope. Then, according to the upper and lower envelope requirements, the block diameter greater than the set diameter is calculated. The block rate range ~ , then the large block rate needs to meet the .

[0093] By increasing the half-hole rate and making the bulk rate fit within the range, the original charge density of the blasthole line can be optimized.

[0094] The optimized line charge density is calculated as:

[0095] ;

[0096] In the formula, Indicates the optimized line charge density; , and represents the error coefficient; Indicates the density of the line charge used in blasting; It indicates the half-hole rate of the blasting at that time; is the semi-porosity required for each lithology; is the rate of large blocks in the current blasting; Indicates the block diameter corresponding to the lower envelope The block rate; Indicates the block diameter corresponding to the upper envelope The block rate.

[0097] Through continuous optimization and adjustment, the optimal blasting parameters under the current rock properties can be obtained.

[0098] Example 2

[0099] This embodiment treats the blast hole based on the arrangement method of the embodiment, such as Figure 4 shown.

[0100] Specifically, all the first blast holes are grooved so that they have two symmetrical V-shaped grooves in the direction of the blast hole line; or, all the first blast holes and the later blast holes are grooved so that they have two symmetrical V-shaped grooves in the direction of the blast hole line; or, all the first blast holes are subjected to shaped charge treatment; or, all the first blast holes and the later blast holes are subjected to shaped charge treatment.

[0101] Grooving treatment will make the cracks expand preferentially along the groove direction, ensuring that the cracks extend a longer distance along the groove direction, thereby achieving the purpose of increasing the distance between the blast holes. The detonation products of the shaped charge are concentrated along the axis of the charge column perpendicular to the surface of the shaped charge cover, so that the detonation products converge into a high-speed, high-pressure, high-energy-density gas jet, thereby increasing the local explosion energy.

[0102] Grooving or shaped charge will generate stress on the blasthole after the explosion. In the embodiment of the present invention, it is specifically reflected in the calculation of the spacing between two adjacent rear blastholes when arranged according to the second method. Therefore, in this embodiment, the spacing between adjacent rear blastholes is calculated by the following formula.

[0103] ;

[0104] ;

[0105]

[0106] In the formula, is a fixed value of rock fracture toughness related to rock properties; represents the crack tip strength factor; is the volume of gas generated by shaped charge explosion; a is the isentropic index; b is the adiabatic index; is the blast hole pressure coefficient of sequential blasting; is the blasting pressure coefficient; represents the volume of explosive in the blast hole; D represents the detonation velocity of the explosive; Indicates average pressure; Indicates the static pressure in the blast hole during sequential controlled blasting; Indicates the instantaneous pressure of the explosive gas when the shaped charge explodes; P K Indicates critical pressure.

[0107] Example 3

[0108] This embodiment provides a method for selecting an arrangement mode based on Embodiment 1 or Embodiment 2, which is described below with reference to Embodiment 2.

[0109] After the test of ten blasting methods, an evaluation was conducted. The cost budget included excavation cost and pyrotechnic cost, and the blasting effect included semi-porosity and flatness. The best method among the ten methods was selected through evaluation.

[0110] The blasting methods were evaluated separately. The excavation cost per meter, the blasting cost per meter, the absolute value of the half-hole rate after blasting and the flatness after blasting were selected as indicators, and four levels of excellent, good, medium and unsatisfactory were established as shown in Table 1.

[0111] Table 1

[0112]

[0113] The membership function of each indicator is established by analyzing the distribution function of the comprehensive evaluation model and the grade division of the above scheme evaluation data.

[0114] The membership functions of excavation cost for unsatisfactory, medium, good, and excellent are as follows.

[0115] Failure:

[0116] ;

[0117] medium:

[0118] ;

[0119] good:

[0120] ;

[0121] good:

[0122] ;

[0123] The membership functions of pyrotechnic cost to unsatisfactory, medium, good and excellent are as follows.

[0124] Failure:

[0125] ;

[0126] medium:

[0127] ;

[0128] good:

[0129] ;

[0130] good:

[0131] ;

[0132] The membership functions of semi-porosity to unsatisfactory, medium, good, and excellent are as follows.

[0133] Failure:

[0134] ;

[0135] medium:

[0136] ;

[0137] good:

[0138] ;

[0139] good:

[0140] ;

[0141] The membership function of the absolute value of flatness to unsatisfactory, medium, good, and excellent is as follows.

[0142] Failure:

[0143] ;

[0144] medium:

[0145] ;

[0146] good:

[0147] ;

[0148] good:

[0149] ;

[0150] The membership function calculated by the above indicators excavation cost, blasting cost, semi-porosity, and absolute value of flatness constitutes a specific membership matrix R

[0151] ;

[0152] The weights of each evaluation index are calculated, a hierarchical structure diagram is established, a judgment matrix is ​​constructed, and a consistency test is performed. Each column element of the judgment matrix is ​​normalized, and the general term of its elements is , Represents the element in the i-th row and j-th column of the judgment matrix, and then adds the normalized judgment matrices of each column row by row , calculate the weight The judgment matrix of the indicators of “explosive work cost”, “half-porosity”, “excavation cost” and “flatness” is shown in Table 2. The results of the normalized elements of the judgment matrix of the indicators themselves are shown in Table 3.

[0153] Table 2

[0154]

[0155] Table 3

[0156]

[0157] The obtained weights are subjected to consistency test, CI = , CR= , where is the maximum eigenvalue of the judgment matrix, RI is the average random consistency, since this matrix has 4 factors, n = 4, and the RI coefficient is 0.89. CR = , the consistency check passed.

[0158] So the weight matrix C = .

[0159] Finally, the obtained weight matrix C and the membership matrix R are calculated to obtain the final result matrix M=C•R, and the comment with the largest value in the result matrix is ​​taken as the comprehensive evaluation result. In this evaluation, the scores of "good", "good", "medium" and "poor" are set to 90, 60, 30 and 0 respectively, and the score set S is obtained. , and then multiply the previous result matrix M by the score set S to get the specific score value. Then choose the method with the highest score value.

[0160] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. Only the preferred embodiments of the present invention are expressed. The description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. As long as there is no contradiction in the combination of these technical features, they should be considered as the scope recorded in this specification.

[0161] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for excavating an underground marine project based on time-controlled blasting, characterized in that: The following steps are involved: Step S1: Arrange in the order of rear explosion hole - front explosion hole - rear explosion hole, and repeat the arrangement; Step S2: setting blasting parameters based on the rock properties of the working face to be blasted; the blasting parameters include charge density of the blasthole line, uncoupling coefficient in the charge structure, detonation time difference and distance between blastholes; Step S3: collecting the half-hole rate and the large block rate after blasting to optimize the charge density of the blasthole line and the distance between blastholes; The spacing between the first blast hole and the second blast hole in step S2 is calculated by the following formula: ； In the formula, is the critical compressive strength of rock, It represents the maximum tangential stress at the point C on the wall of the later explosion hole B that is closest to the earlier explosion hole A; represents the lateral stress coefficient; P0 represents the initial pressure acting on the hole wall after the blasting of the first blast hole; R A Indicates the radius of the first blast hole A; R B represents the radius of the post-explosion hole B; represents the Poisson's ratio of the rock mass; L represents the distance between the first blast hole and the last blast hole; The spacing between adjacent post-blast holes is calculated using the following formula: ； In the formula, is the rock fracture toughness, which is a fixed value related to the rock properties; represents the crack tip strength factor; Represents the static pressure in the blast hole during sequential controlled blasting; R B represents the radius of the post-explosion hole B; represents charge density; D represents explosive detonation velocity; k1 represents uncoupling coefficient; k2 represents charge coefficient; Indicates the spacing between post-blast holes.

2. The method for excavating an underground marine project based on sequential controlled blasting according to claim 1, characterized in that: In step S1, the first blasthole is subjected to a V-shaped grooving operation or a shaped charge treatment; or, in step S1, the first blasthole and the subsequent blasthole are subjected to a V-shaped grooving operation or a shaped charge treatment.

3. The method for excavating an underground marine engineering project based on time-controlled blasting according to claim 2, characterized in that: After the V-groove operation or shaped charge treatment, the spacing between two adjacent post-blast holes is replaced by the following formula: ； ； ； is the rock fracture toughness, which is a fixed value related to the rock properties; represents the crack tip strength factor; Indicates average pressure; Indicates the static pressure in the blast hole during sequential controlled blasting; Indicates the instantaneous pressure of the explosive gas during V-grooving operation or shaped charge blasting; R B represents the radius of the post-explosion hole B; represents charge density; D represents explosive detonation velocity; k1 represents uncoupling coefficient; k2 represents charge coefficient; Indicates the spacing between post-blast holes; It indicates the pressure coefficient of the blast hole in the sequential blasting; Indicates the V-groove operation or concentrated burst pressure coefficient; P K Indicates critical pressure; It indicates the volume of gas generated by V-grooving operation or shaped charge blasting; It represents the charge volume of the blast hole; a is the isentropic index; b is the adiabatic index.

4. The method for excavating an underground marine engineering project based on sequential controlled blasting according to claim 1, characterized in that: In step S3, optimization is performed using the following formula: ； In the formula, It represents the optimized line charge density; , and represents the error coefficient; Indicates the density of the wire charge used in blasting; It indicates the half-hole rate of the blasting at that time; is the half porosity required for each lithology; is the rate of large blocks in the current blasting; Indicates the block diameter corresponding to the lower envelope The block rate; Indicates the block diameter corresponding to the upper envelope The block rate.

5. The method for excavating an underground marine engineering project based on time-controlled blasting according to claim 2, characterized in that: In step S2, the arrangement mode is selected by the following method: Step S21: Experimenting with all arrangements; Step S22: selecting excavation cost per meter, pyrotechnic cost per meter, half-hole ratio after blasting and absolute value of flatness after blasting as indicators, and establishing evaluation rules including four levels of excellent, good, medium and unsatisfactory; Step S23: Based on the experimental results and the evaluation rules, after calculating the membership matrix and the weight matrix, a comprehensive score is calculated, and the arrangement method with the highest comprehensive score is selected to proceed to the subsequent steps.

6. The method for excavating an underground marine engineering project based on sequential controlled blasting according to claim 1, characterized in that: Detonation time difference between the first blast hole and the last blast hole Set to: =25ms~80ms.

7. The method for excavating an underground marine engineering project based on time-controlled blasting according to claim 1, characterized in that: The uncoupling coefficient in the charge structure is set to 2~4.

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