Geological vibration assessment method under multi-medium underwater explosion strong nonlinear fluid-solid coupling condition

Abstract

The invention discloses a geological vibration assessment method under a multi-medium underwater explosion strong nonlinear fluid-solid coupling condition. The method comprises the following steps: (1) acquiring and constructing terrain point cloud data by adopting an unmanned aerial vehicle and an unmanned ship; (2) carrying out an underwater explosion test under typical working conditions, and recording vibration speed-time data by explosion vibration monitors arranged at each measuring point; (3) a land measuring point vibration velocity peak value calculation model under the multi-medium underwater explosion condition can be obtained; (4) performing regression fitting on the explosion vibration data by using the measurement point vibration speed peak value calculation model V to obtain explosion vibration speed attenuation formulas under different working conditions; and (5) according to a calculation result, comparing safety vibration threshold values of different types of buildings and anti-seismic requirements, and evaluating safety conditions of the buildings and the structures. By establishing the multi-medium model, the propagation and interaction of the strong nonlinear load generated by underwater explosion in different media can be accurately simulated, and the evaluation accuracy is improved.

Description

Technical Field

[0001] The invention relates to a geological vibration assessment method under the condition of strong nonlinear fluid-solid coupling of multi-media underwater explosion, belonging to the field of blasting. Background Art

[0002] In the fields of engineering construction, military research, etc., underwater explosion tests are common test methods. However, the strong nonlinear loads generated by the explosion, such as the underwater shock wave and rock stress wave generated by the explosion, will cause vibration effects. The vibration effects exceeding the specified blasting safety threshold will pose a potential risk of damage to buildings or structures near the coast. Therefore, it is very important to evaluate the explosion vibration of coastal protection targets.

[0003] The calculation and evaluation of vibration of coastal protection targets caused by underwater explosions is a multi-media strong nonlinear fluid-solid coupling problem, which lacks a systematic and accurate method. The use of traditional theoretical analytical methods and numerical simulation calculations will greatly simplify the actual working conditions, resulting in large errors between the calculation and evaluation results and the actual situation. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a method for assessing geological vibrations under conditions of strong nonlinear fluid-solid coupling of a multi-media underwater explosion. By establishing a multi-media model, the propagation and interaction of strong nonlinear loads generated by the underwater explosion in different media can be accurately simulated, thereby improving the accuracy of the assessment.

[0005] Technical solution: To solve the above technical problems, the present invention provides a method for evaluating geological vibration under conditions of strong nonlinear fluid-solid coupling of a multi-media underwater explosion, comprising the following steps:

[0006] (1) Use drones and unmanned boats to collect and construct terrain point cloud data;

[0007] (2) Conduct underwater explosion tests under typical working conditions. The explosion test conditions shall include at least two explosive charges, two charge elevations, at least two water bottom elevations of the explosion point, two explosion point coast distances, and at least two distances, two measurement point elevations, and two sand layer thicknesses of 1m and 3m for the explosion vibration measurement points on the coast. After the explosives explode in the water, the explosion vibration monitors arranged at each measurement point record the vibration velocity-time data;

[0008] (3) The peak value V of the explosion vibration velocity at a certain point on land is related to the explosion TNT equivalent, the properties of various media, the distance from the explosion point, and the size parameters. The influencing factors of each medium are decomposed, and multiple media such as water, bottom sand layer, and rock mass are considered. The input conditions are set as follows: Q: explosion TNT equivalent; H 1 : The bottom elevation of the explosion point; H 2 : Charge height; H 3 : elevation of the land measuring point; R1 : Horizontal distance from the explosion point to the coast; R 2 : Horizontal distance from the burst point to the measuring point; L: Thickness of the bottom sand layer, factors affecting the burst point distance: Factors affecting the depth of the burst point: Factors affecting shock wave attenuation in water: Factors affecting the elevation of measuring points: Seabed sand layer influencing factors:

[0009] Combining the above five types of influencing factors, the calculation model of the peak value of vibration velocity of the onshore measuring point under the condition of multi-media underwater explosion can be obtained as follows:

[0010]

[0011] (4) The explosion vibration data were regressed and fitted using the peak value calculation model V of the vibration velocity at the measuring point. The vibration test data under different working conditions were regressed to obtain the corresponding A 1 -A 5 and B 1 -B 5 value, and obtain the explosion vibration velocity attenuation formula under different working conditions;

[0012] (5) The peak vibration velocity at any location near the explosion area is calculated based on the vibration velocity peak attenuation formula. Based on the calculation results, the safety vibration thresholds of different types of buildings and seismic requirements are compared to evaluate the safety of buildings and structures.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0014] 1. By establishing a multi-media model, the propagation and interaction of strong nonlinear loads generated by underwater explosions in different media can be accurately simulated, thus improving the accuracy of the assessment.

[0015] 2. Using the shock wave and stress wave attenuation theory, the attenuation characteristics of explosion shock waves and stress waves in different media can be described more accurately, providing a scientific basis for evaluation.

[0016] 3. This method can rely on less explosion vibration velocity monitoring data to quickly evaluate the vibration safety of underwater explosions on buildings or structures at any location on the coast, providing an important reference for engineering design and safety protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a site schematic diagram of the present invention.

[0018] Figure 2 This is a schematic diagram of the test area and surrounding conditions in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Embodiment 1:

[0021] A method for evaluating geological vibration under strong nonlinear fluid-solid coupling conditions of a multi-media underwater explosion comprises the following steps:

[0022] S1. Use drones and unmanned boats to collect and construct terrain point cloud data;

[0023] S2. This project plans to carry out three 100kgTNT and two 200kgTNT equivalent explosion source actual explosion tests. The design of the test conditions should take into account various typical geological impact response characteristics. During the test, it is required to measure the ground vibration response of the proposed project, a medical university, Oceanwide Construction, a certain military barracks, etc., and evaluate the safety of the engineering facilities; evaluate the safety impact of the underwater explosion on the surrounding environment such as a certain medical university, Oceanwide Construction, and a certain military barracks. The explosion test location is located in a certain sea area. During the underwater test, there are proposed projects, a medical university, Oceanwide Construction, a certain military barracks, etc. The distance between each protected target and the underwater explosion point is about 1.9km at the farthest and 367m at the closest. Figure 2 shown.

[0024] The landform of the sea area near the project construction project of this test is underwater slope landform, with high terrain in the north and low terrain in the south, showing a gentle slope. The seabed is covered with Quaternary silt sand, gravel sand, round gravel, etc., and the underlying quartzite slate interlayers of the Nanfen Formation of the Qingbaikou System; the land area is a sea erosion cliff landform, with steep cliffs and large terrain fluctuations. The bedrock of the cliff is the interlayer of quartzite slate of the Nanfen Formation of the Qingbaikou System.

[0025] According to the results of this survey, combined with regional engineering geological data, the strata revealed by drilling in the field can be divided into the Quaternary Holocene (Q4) and the Qingbaikou Nanfen Formation (Qbn) bedrock. Now they are described from new to old as follows:

[0026] Quaternary Holocene marine sedimentary layer (Q4m)

[0027] Silt (2-10): gray-brown, gray-black, slightly dense to medium dense, mainly composed of quartz and feldspar, with gaps filled with clay. The exposed layer is 1.10 to 1.90 meters thick, with a bottom elevation of -12.10 to -12.80 meters. This layer is only exposed in boreholes ZK04 and ZK11.

[0028] Gravel sand (2-11): gray-black to gray-brown, saturated, medium-dense state, the main mineral component is quartz, containing a small amount of clay, locally intercalated with thin layers of coarse sand lenses, containing a small amount of shells, containing a small amount of organic matter, and slightly fishy smell. The exposed layer is 2.90 to 4.70 meters thick, and the bottom elevation is -15.10 to -10.90 meters. This layer was exposed in ZK01 to ZK04 and ZK11 drill holes.

[0029] Gravel (2-30): gray-brown, slightly dense to medium dense, mainly composed of quartz and feldspar, with gaps filled with clay and sand. The exposed layer is 1.00 to 3.00 meters thick, with a bottom elevation of -11.90 to -7.90 meters. This layer was exposed in boreholes ZK01, ZK03, ZK04, and ZK08.

[0030] Nanfen Formation (Qbn) of the Qingbaikou system.

[0031] Interlayers of medium-weathered quartzite and slate (11-13): grayish yellow to grayish white, residual structure, layered structure, the main mineral components are mica and quartz, slate and quartzite are interlayered, with slate as the main component, the weathering joints and fissures of the rock mass are relatively developed, the rock mass is relatively broken, and the rock core is blocky, cake-shaped, and short columnar. The saturated uniaxial compressive strength of slate is 12.3~23.0MPa, the standard value is 12.63MPa, and it belongs to soft rock-relatively soft rock; the saturated uniaxial compressive strength of quartzite is 23.5~35.9MPa, the standard value is 27.42MPa, and it belongs to relatively soft rock-relatively hard rock. The rock mass is relatively broken to relatively complete, and the basic quality grade of the rock mass is III~V, the top burial depth of the layer is 0.00~6.50 meters, and the top elevation of the layer is -15.10~-42.00 meters.

[0032] (5) Explosive sources and explosive devices

[0033] sequence Material Name Specification unit quantity 1 Explosion Source 1# 100kg piece 7 2 Explosion Source 2# 200kg piece 1 3 TNT explosive charge 200g / piece piece 30 4 Detonating cord 1000m roll 20 5 Electric detonator 8# pieces 15

[0034] (6) Detonation method

[0035] The detonation method selects the method of setting both laser detonation and electric detonation at the same time. The main detonation device is a laser detonation device, which is used to test the detonation source; the auxiliary detonation device is an electric ignition system, which is used to detonate the explosion source after the main detonation device fails to detonate;

[0036] (7) There are at least two explosive charges: 100kg and 200kg; two charge heights: 20m and 10m; at least two water bottom heights at the explosion point: 40m and 30m; two explosion point coast distances: 360m and 200m; at least two distances at the coastal land explosion vibration measurement points: 380m and 500m; two measurement point heights: 5m and 10m; two sand layer thicknesses: 1m and 3m. After the explosives explode in the water, the explosion vibration monitors arranged at each measurement point record the vibration velocity-time data. The collected data are as follows:

[0037]

[0038] S3. By analyzing the collected data, the output is submitted to locate the explosion vibration velocity peak value V (cm / s), and the input conditions are set as: Q: explosion TNT equivalent (kg); H 1 : absolute value of the bottom elevation at the explosion point (m); H 2 H: absolute value of charge height (m); 3 : elevation of land measuring point (m); R 1 : Horizontal distance from explosion point to coast (m); R 2 : Horizontal distance from the burst point to the measuring point (m); L: Thickness of the bottom sand layer (m), the impact factor of the burst point distance: Factors affecting the depth of the burst point: Factors affecting shock wave attenuation in water: Factors affecting the elevation of measuring points: Seabed sand layer influencing factors:

[0039] Combining the above five types of influencing factors, the calculation model of the peak value of vibration velocity of the onshore measuring point under the condition of multi-media underwater explosion can be obtained as follows:

[0040]

[0041] (4) The explosion vibration data were regressed and fitted using the peak value calculation model V of the vibration velocity at the measuring point. The vibration test data under different working conditions were regressed to obtain the corresponding A 1 -A 5 and B 1 -B 5 value, and obtain the explosion vibration velocity attenuation formula under different working conditions;

[0042] The parameters obtained are: A 1 -A 5 and B 1 -B 5:

[0043] A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 400 1.16 200 1.25 1.05 1.5 0.15 1.25 0.75 0.15

[0044]

[0045] The peak vibration velocity at any position near the explosion area is calculated according to the vibration velocity peak attenuation formula. According to the calculation results, the safety vibration thresholds of different types of buildings and seismic requirements are compared to evaluate the safety of buildings and structures. In the case of the following table, the peak explosion vibration velocity is 1.472cm / s, which is less than the safety threshold of 2.5cm / s for general buildings specified in the "Explosion Safety Regulations", and it can be evaluated as a safe explosion test condition.

[0046]

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for assessing geological vibrations under conditions of strong nonlinear fluid-solid coupling of multi-media underwater explosions, characterized in that: The following steps are involved: (1) Use drones and unmanned boats to collect and construct terrain point cloud data; (2) Conduct underwater explosion tests under typical working conditions. The explosion test conditions shall include at least two types of explosive loads and two types of charge elevations. The explosion point location shall include at least two types of water bottom elevations and two types of explosion point distances. The explosion vibration measurement points on the coast shall include at least two distances and two types of elevations. After the explosives explode in the water, the explosion vibration monitors arranged at each measurement point shall record the vibration velocity-time data. (3) The peak value V of the explosion vibration velocity at a certain point on land is related to the explosion TNT equivalent, the properties of various media, the distance from the explosion point, and the size parameters. The influencing factors of each medium are decomposed, and various media such as water, underwater sand layer, and rock mass are considered. The input conditions are set as follows: Q: explosion TNT equivalent; H1: underwater elevation of the explosion point; H2: charge elevation; H3: elevation of the onshore measuring point; R1: horizontal distance from the explosion point to the coast; R2: horizontal distance from the explosion point to the measuring point; L: thickness of the underwater sand layer. The influencing factors of the explosion point distance are: Factors affecting the depth of the burst point: Factors affecting shock wave attenuation in water: Factors affecting the elevation of measuring points: Seabed sand layer influencing factors: The peak value calculation model of vibration velocity of land measuring points under multi-media underwater explosion conditions can be obtained as follows: (4) The explosion vibration data are regressed and fitted using the peak value calculation model V of the vibration velocity at the measuring point. The vibration test data under different working conditions are regressed to obtain the corresponding A1-A5 and B1-B5 values, and the explosion vibration velocity attenuation formula under different working conditions is obtained; (5) The peak vibration velocity at any location near the explosion area is calculated based on the vibration velocity peak attenuation formula. Based on the calculation results, the safety vibration thresholds of different types of buildings and seismic requirements are compared to evaluate the safety of buildings and structures.

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