Monitoring and Prediction of the Vibration Intensity of Seismic Waves Induced in Underwater Rock by Underwater Drilling and Blasting

All underwater drilling and blasting operations generate seismic waves.However,due to a lack of suitable vibration sensing instruments,most studies on the propagation of seismic waves have been limited to shorelines near construction areas or wharfs,whereas comparatively few studies have beerconducted on the larger seafloor itself.To address this gap,a seafloor vibration sensor system was developed and applied in this study that consists of an autonomous acquisition storage terminal,soft-ware platform,and hole-plugging device that was designed to record the blasting vibration intensities received through submarine rocks at a given measurement point.Additionally,dimensional analyses were used to derive a predictive equation for the strength of blast vibrations that considered the in fluence of the water depth.By combining reliable vibration data obtained using the sensor system in submarine rock and the developed predictive equation,it was determined that the water depth was ar important factor influencing the measured vibration strength.The results using the newly derivedequation were compared to those determined using the Sadowski equation,which is commonly used on land,and it was found that predictions using the derived equation were closer to the experimental values with an average error of less than 10%,representing a significant improvement.Based on these results the developed sensor system and preliminary theoretical basis was deemed suitable for studying the propagation behavior of submarine seismic waves generated by underwater drilling and blasting operations.

Monitoring and analysis of shock wave in water for underwater drilling blasting

Taking the underwater reef blasting in Gulei sea channel of Xiamen Port as an example,the forming characteristic of shock wave in water for underwater drilling blasting is analyzed.By field monitoring,the pressure of shock wave in water for different distances is attained;the major parameters such as pressure amplitude and positive action time,and the propagation attenuation rule of shock wave in water are analyzed in this paper.The results can be helpful for engineering design and construction and environmental safety assessment.

Vibration velocity and frequency of underwater short-hole blasting

Based on the measuring data of underwater blasting vibration and theregression analysis results of these data, two formulae usually used of blasting vibration velocitywere compared. Factors that can affect blasting vibration and frequency were summarized andanalyzed. It is thought that the effect of the number of freedom face and burden direction onblasting vibration should be considered during blasting design. Based on the relevant researchresults and the regression results of these data, a formula to calculate under water blastingfrequency was put forward.

Blast Pressure Measurements of an Underwater Detonation in the Sea

Blast pressure measurements of a controlled underwater explosion in the sea were carried out.An explosive of 25-kg trinitro-toluene(TNT)equivalent was detonated,and the blast pressures were recorded by eight diferent high-performance pressure sensors that work at the nonresonant high-voltage output in adverse underwater conditions.Recorded peak pressure values are used to establish a relationship in the well-known form of empirical underwater explosion(UNDEX)loading formula.Constants of the formula are redetermined by employing the least-squares method in two diferent forms for best ftting to the measured data.The newly determined constants are found to be only slightly diferent from the generally accepted ones.

Typical Underwater Tunnels in the Mainland of China and Related Tunneling Technologies

In the past decades, many underwater tunnels have been constructed in the mainland of China, and great progress has been made in related tunneling technologies. This paper presents the history and state of the art of underwater tunnels in the mainland of China in terms of shield-bored tunnels, drill-and-blast tunnels, and immersed tunnels. Typical underwater tunnels of these types in the mainland of China are described, along with innovative technologies regarding comprehensive geological prediction, grouting-based consolidation, the design and construction of large cross-sectional tunnels with shallow cover in weak strata, cutting tool replacement under limited drainage and reduced pressure conditions, the detection and treatment of boulders, the construction of underwater tunnels in areas with high seismic intensity, and the treatment of serious sedimentation in a foundation channel of immersed tunnels. Some suggestions are made regarding the three potential great strait-crossing tunnels-the Qiongzhou Strait-Crossing Tunnel, Bohai Strait-Crossing Tunnel, and Taiwan Strait-Crossing Tunnel--and issues related to these great strait-crossing tunnels that need further study are proposed.

Experimental investigations on small-and full-scale ship models with polyurea coatings subjected to underwater explosion

Nowadays, the mitigation of damage to a ship caused by the underwater explosion attracts more and more attention from the modern ship designers. In this study, two kinds of scale tests were conducted to investigate the effects of polyurea coatings on the blast resistance of hulls subjected to underwater explosion. Firstly, small-scale model tests with different polyurea coatings were carried out. Results indicate that polyurea has a better blast resistance performance when coated on the front face, which can effectively reduce the maximum deflection of the steel plate by more than 20% and reduce the deformation energy by 35.7%-45.4%. Next, a full-scale ship(approximately 50 m × 9 m) under loadings produced by the detonation of 33 kg of spherical TNT charges was tested, where a part of the ship was coated with polyurea on the front face(8 mm + 24 mm) and not on the contrast area. Damage characteristics on the bottom were statistically analyzed based on a 3D scanning technology, indicating that polyurea contributes to enhancing the blast protection of the ship. However, damage results of this test were different from those of the small-scale tests. Moreover, the deformation area of the bottom with polyurea was greatly increased by 40.1% to disperse explosion energy, a conclusion that cannot be drown from the small-scale tests.

Underwater explosion effects of 60 mm H.E. mortar bomb on a cylindrical concrete structure-PIT

PIT tests are usually performed when a mass distribution of High Explosive(H.E) projectile fragments is required. This paper shows the underwater detonation effects of 60 mm, M90 H.E. mortar bomb filled with Comp. B on cylindrical concrete structure(concrete pipe closed at one end-similar to a PIT test)which is 2 m high(inner height) with inner diameter of also 2 m. Thickness of both wall and bottom of a pipe is 0.35 m. Detailed characteristics of concrete which is used for manufacturing of a pipe are specified. Mortar bomb is submerged directly in to the water(no free airspace around the bomb) with the nose pointing to the bottom of a pipe. Number and mass of fragments after detonation are presented by table and photographs. Fragments of dummy fuze, through which blasting cap was protruded, are collected and reassembled to form a shape of a fuze after detonation where expanding of fuze material due to a detonation products is visualized. After underwater detonation, detonation of the same mortar bomb is performed in an empty pipe and the effects of this kind of detonation are observed. Distance at which fragments generated from submerged mortar bomb will not reach concrete pipes wall is also determined.

Analysis of fracture mechanism for surrounding rock hole based on water-filled blasting

The principles of fracture development during underwater blasting are examined based on explosion and impact dynamics,fluid dynamics,fracture dynamics,and field testing.The research reveals that the fracturing of the surrounding rock during underwater blasting is due to the combined action of shock and stress waves for the initial rock breakage and subsequent water expansion.The fracture development model for the surrounding rock of a drilling hole during underwater blasting is established.The rock fracturing range under the combined action of shock and stress waves is developed,as well as the fracture propagation rules after the wedging of the water medium into the fractures.Finally,the results of deep-hole underwater blasting tests on large rocks confirm the efficient utilization of explosive in the hole to improve the safety conditions.Accordingly,safe and static rock breaking under the detonation of high-effect explosive can be achieved.In addition,super-dynamic loading from the explosions and static loading from the water medium in the hole can be adequately combined for rock breaking.

Effect of GGBS on performance deterioration of non-dispersible underwater concrete in saline soil

In saline soil areas,there are a large number of ions in soil or water environments,such as Cl^(-)and SO_(4)^(2-),which have strong corrosive interactions with buildings.To study the deterioration of non-dispersible underwater concrete in sulfate,chloride,and mixed salt environments,the compressive strength and deterioration resistance coefficient of the studied concrete mixed with different amounts of ground granulated blast-furnace slag(GGBS)were analyzed in this paper.At the same time,the micro morphology and corrosion products distribution of the studied concrete were observed by means of SEM,plus XRD diffraction,TG-DTG and FT-IR analyses to explore the influence of corrosive solutions on the hydration products of concrete.We also analyzed the mechanism of improving the deterioration resistance of the studied concrete by adding GGBS in a saline soil environment.The results show that the compressive strength of the studied concrete in a chloride environment was close to that in a fresh water environment,which means that chloride has no adverse effect on compressive strength.The deterioration of the studied concrete was most serious in a sulfate environment,followed by mixed salt environment,and the lowest in a chloride environment.In addition,by adding GGBS,the compressive strength and deterioration resistance of the studied concrete could be effectively improved.

基于PSO-CNN-XGBoost水下柱形装药峰值超压预测

为探索水下柱形装药结构、爆距等参数与水下柱形装药峰值超压的关系,将装药样本数据视为二维数据,建立粒子群优化(Particle Swarm Optimization,PSO)算法、一维卷积神经网络(1D Convolutional Neural Network,1DCNN)和极端梯度提升(Extreme Gradient Boosting,XGBoost)的水下柱形装药峰值超压融合预测算法。采用相关性分析与数据可视化方法,分析装药结构参数、爆距与峰值超压之间的关联关系。设计1DCNN深度网络挖掘不同长径比、爆距等参数与峰值超压之间的纵向时序关系。运用XGBoost算法寻找装药结构参数、爆距与峰值超压之间的横向非线性关系,提升小样本数据的预测精度。使用PSO算法优化1DCNN和XGBoost的超参数,获得最优算法结构。研究结果表明,在包含10种智能算法的对比实验中,PSO-CNN-XGBoost水下柱形装药峰值超压预测算法在精度、稳定性、拟合程度上均高于其他模型。

微差爆破在港口工程中的应用

考虑到地质条件的复杂性和输油管等重要设施的存在,水下炸礁作为港口建设和航道疏浚中的重要工作手段需要确保工程的安全性。为了减少爆破产生的冲击波、震荡及爆破涌浪对周围环境的危害,对地质条件进行充分分析,并选取合适的爆破自由面以降低爆破振动的影响。在进行水下炸礁工作时,开展试爆研究,通过调整爆破参数如装药量和引爆时间,达到最佳的效果;通过设计最佳的装药结构,提高爆破的稳定性和安全性。研究成果可为地质坚硬、水深较深、施工条件复杂以及需要确保施工区内重要建筑安全的水下炸礁工程提供技术参考。

水下钻孔爆破技术新发展

水下钻孔爆破虽然经过了几十年的工程实践和理论研究,但成果散乱且不系统,有些资料还相互矛盾,落后的施工工艺及装备还在使用,难以使水下钻孔爆破设计与施工实现正规化、现代化和智能化。通过查阅近二十年的文献资料、现场调研和工程实践等,对水下钻孔爆破的理论、装备、技术与工艺和有害效应控制等最新成果进行梳理与总结,展现水下钻孔爆破最新发展成果。为实际工程项目爆破方案与参数设计、施工工艺与装备选择、有害效应控制与防护措施等提供理论及技术支撑,从而解决水下钻孔爆破中遇到的疑难问题,达到优质安全高效之目的。

聚能装药水下破坏双层靶板数值模拟研究

针对水下爆破舰船以及构筑物装药的高效要求,采用锆基非晶合金作为聚能装药药型罩材料,并采用有限元数值计算方法,对比分析了锆基非晶合金和传统紫铜材料作为药型罩对水下双层靶板毁伤性能分析。结果表明,锆基非晶合金材料药型罩聚能装药较之紫铜材料药型罩在金属射流速度上性能提升14.9%,破板后效(穿靶后射流剩余速度)提升37.3%,可为爆破钢结构构筑物提供参考。

改进的组合夹层板水下抗爆性能分析

夹层板因其优异的抗冲击性能广泛应用于舰船防爆防撞领域.为了探究不同芯层结构夹层板水下抗爆性能,基于当前性能优异的V型夹层板进行适当改进,利用LS-DYNA软件对当前的V型夹层板和改进结构的防护性能进行分析,对变形模式、速度和加速度模式以及吸能效应进行数值模拟对比分析.经过综合分析与比较,发现改进的V-X型夹层板各方面性能都要优于传统的V型夹层板.然后分析了结构参数对改进夹层板结构抗爆性能的影响,结果表明:V-X型夹层板的面板厚度、芯层厚度对上下面板的塑性位移有较大影响,面板和芯层厚度越大,上下面板产生的位移越小,但是吸能效率逐渐降低.面板-芯层的夹角小于40°时,对夹层板的防护性能较好;芯层高度也会对结构整体的抗爆性能产生影响,经过综合比较,芯层高度为70 mm时,其抗爆性能较好.研究工作可为新型舰船的结构设计提供借鉴.

水下爆炸冲击下箱型隧道结构破坏试验及数值模拟

针对水下爆炸荷载作用下混凝土隧道结构的动态响应、损伤演化及其破坏问题,本文采取室内模型试验与数值计算相结合的方法,根据东湖水下隧道设计了比尺为40∶1的试件,开展了水下箱型混凝土隧道缩比模型的爆炸试验,通过监测应变信号,比较了不同乳化炸药当量下混凝土隧道试件的动态响应规律,通过测量破坏范围的大小、裂缝扩展的长度,调查了箱型隧道缩比模型试件在水下爆破荷载作用下的破坏形式;采用ANSYS/LSDYNA中S-ALE算法对试验进行了1∶1建模仿真分析,对照试验数据及破坏形态,发现模拟结果与试验结果基本一致,同时对仿真结果进一步分析得到了水下爆炸冲击波的传播完整过程和试件结构的变形规律,通过对测点应变、位移数据的统计分析,揭示了箱型隧道试件在爆炸荷载下的动态响应机理。结果表明:箱型混凝土隧道结构在横向上的应变远大于纵向上应变;隧道破坏位置主要集中在爆源附近区域以及结构转角位置,验证了S-ALE算法能够较为准确的模拟出水下爆炸下结构的动态响应及损伤演化。

A novel method for simulating nuclear explosion with chemical explosion to form an approximate plane wave: Field test and numerical simulation

A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection infrastructures.With the increase in nuclear explosion power,underground protection engineering enabled by explosion-proof impact theory and technology ushered in a new challenge.This paper proposes to simulate nuclear explosion tests with on-site chemical explosion tests in the form of multi-hole explosions.First,the mechanism of using multi-hole simultaneous blasting to simulate a nuclear explosion to generate approximate plane waves was analyzed.The plane pressure curve at the vault of the underground protective tunnel under the action of the multi-hole simultaneous blasting was then obtained using the impact test in the rock mass at the site.According to the peak pressure at the vault plane,it was divided into three regions:the stress superposition region,the superposition region after surface reflection,and the approximate plane stress wave zone.A numerical simulation approach was developed using PFC and FLAC to study the peak particle velocity in the surrounding rock of the underground protective cave under the action of multi-hole blasting.The time-history curves of pressure and peak pressure partition obtained by the on-site multi-hole simultaneous blasting test and numerical simulation were compared and analyzed,to verify the correctness and rationality of the formation of an approximate plane wave in the simulated nuclear explosion.This comparison and analysis also provided a theoretical foundation and some research ideas for the ensuing study on the impact of a nuclear explosion.

减振材料对圆柱水池爆破振动规律的影响

在水下爆炸理论与技术的应用研究中,爆炸水池是十分重要的基础试验装置。研究爆炸水池爆破振动效应和减振对于圆柱形爆炸水池使用过程中的振动控制具有指导意义。为研究圆柱形水池内部装药爆炸对周围地面产生的爆破振动并寻求合适的减振材料,选取了建筑碎石、SD型橡胶垫2种减振材料,在小型爆炸水池中进行了单药包在无减振、建筑碎石和SD型橡胶垫减振3种模式下的爆炸试验,对采集到的爆破振动信号进行峰值振速分析、EEMD-HHT(ensemble empirical mode decomposition-Hilbert-Huang transform)处理及小波包分析。结果表明:爆炸水池周围地面的爆破振动包含爆炸冲击波导致的振动、水池跳动导致的触地振动,通过Hilbert瞬时能量分析可以有效识别水池产生的跳动;碎石减振和SD型橡胶减振垫模式下的振速较无减振模式下的振速分别降低53.0%和43.1%,振动能量分别降低64.9%和57.4%;3种减振模式下爆破振动信号的频率主要分布在10~80 Hz区间;无减振、建筑碎石减振、SD型橡胶垫3种减振模式下10~40 Hz频带的能量占比分别为79%、69%、66%,40~80 Hz频带的能量占比分别为11%、29%、31%。碎石和SD型橡胶垫具有吸能、减少低频成分和增加高频成分的效果,可有效降低近处测点的峰值振速。碎石减振模式下振动信号频带的能量分布较SD型橡胶垫模式下的能量分布更加均匀。

钢筋混凝土拱的水下抗爆性能

为探究水下爆炸荷载作用下钢筋混凝土拱的动力响应特性和破坏特征,制作了两个钢筋混凝土拱试件,并开展了水下爆炸试验。试验分为拱外爆炸和拱内爆炸两组,采用10 g乳化炸药,试验时爆源距结构面最小距离为10 cm(起爆点位于拱结构正上方和正下方),通过传感器记录爆炸试验中钢筋混凝土拱典型断面处的水压力及加速度时程曲线。基于Arbitrary Lagrange-Euler(ALE)算法,建立了空气-水-炸药-钢筋混凝土拱等多介质动态耦合作用模型,将数值模拟结果与试验结果对比,验证了数值方法的可靠性。采用验证后的数值模型进一步研究了拱外及拱内爆炸荷载作用下钢筋混凝土拱的动力响应差异。结果表明:相同炸药当量下,内部爆炸有更多的能量作用于混凝土拱,使结构的动力响应更强烈;外部爆炸下,拱顶、拱腰处产生较大裂缝;内部爆炸时,迎爆面裂缝数量明显增多,拱肩位置出现裂缝。钢筋混凝土拱形结构抵抗外部爆炸荷载的能力明显强于内部爆炸荷载。

工业电子雷管在水下爆破中的应用

为解决水下爆破作业中所遇到的相关问题,采用数值模拟和工程试验的方法,分析了不同起爆方式对爆破有害效应的影响,同时对比了采用工业电子雷管孔内不同起爆顺序对爆破效果影响及气泡帷幕对降低冲击波的影响。数值模拟结果表明:采用工业电子雷管逐孔起爆方式在控制爆破振动及冲击波中具有较大优势,最大降振率达71.63%,最大削波率达73.20%,采用孔内上部优先起爆的顺序可以有效地改善大块率及根底现象,水下气泡帷幕较大程度上削弱了爆破冲击波,工业电子雷管在水下爆破中的应用可减弱爆破有害效应、改善爆破效果、避免盲炮,可为同类工程提供相应参考。

水下钻孔爆破水不耦合装药的减振效应研究

为了研究水不耦合装药爆破在水下爆破中的减振效应,以减少对邻近建筑物等被保护对象的危害,分别采用理论推导和现场试验方法,研究了水不耦合装药爆破振动的衰减规律。在理论推导中,根据牛顿第三定律、介质连续条件和波的动量守恒定律,通过计算波阻抗比,分别推导了水不耦合装药爆破和耦合装药爆破两种情况下,炸药爆炸冲击波在水体和岩体之间反射、透射之后的质点振动速度,得出水不耦合装药爆破爆炸冲击波传入岩体内的质点振动速度衰减率。计算结果表明,水不耦合装药爆破炸药爆炸冲击波经水体传入岩体后,岩体质点振动速度仅为炸药质点振动速度的3.8%;与耦合装药爆破相比,岩石质点振动速度减少93.10%。现场实验结果表明,综合采取水不耦合装药、逐孔起爆、精确限定单孔装药量和一次起爆最大装药量,以及其他减震措施,基于实测的爆破振动数据,动态优化调整爆破参数,减少了爆破振动和水中冲击波对被保护物的危害,保障了爆破质量和工程进度。无论是理论推导还是现场试验,均表明水不耦合装药爆破在水下爆破中具有明显的减振作用,计算得出的质点振动速度衰减率具有理论指导意义,而在现场试验获得的实际效果,为水下爆破工程的振动控制,提供了实践经验和借鉴,并形成了一套水下钻孔水不耦合装药爆破技术施工工艺。