Modeling Effects of Chemical Explosives for Excavation on Moon

Twelve model tests of chemical explosives (1 g and 0.25 g) of PETN were conducted at 1 g (? = ?6?g [moon]) and 10 g (? = ?60?g [moon]) using the geotechnical centrifuge to determine the effect of chemical explosives on cratering and loosening a compacted lunar simulant prior to excavation. Even small depths of burial of the explosives were found to increase markedly the volume and lip of resulting apparent craters; optimum depths of burial were not pinpointed. Volumes of craters from PETN charges of different weights but equal depths of burial, were related as V? = ?kW084 when charges were fully buried, but not for surface tangent charges. Tests conducted at 1 g and 10 g showed no detectable difference in crater volumes for the depths of burial tested. Constraints to extrapolating the research to the lunar surface (using simulant rather than actual lunar soil; working in earth′s atmosphere rather than in a vacuum; and working at greater than 1 g [moon]) are acknowledged.     

基于粒状铵油炸药的巷道光面爆破技术及应用

某铜矿矿(岩)体层理裂隙发育,巷道掘进爆破施工过程中,卷装乳化炸药装药有时比较困难,爆破效果较差。在总结巷道掘进施工问题的基础上,提出采用光面爆破技术,进行巷道掘进爆破,巷道成型较好,但装药效率低、成本偏高等。将散装粒状铵油炸药应用于掘进爆破中,通过理论分析,结合试验验证后,进行全面推广。应用结果表明:将粒状铵油炸药应用于巷道光面爆破中,能有效提高装药效率,爆破效果更趋于稳定,同时达到了降本增效的效果,取得了很好的经济和社会效益,也为在国内巷道掘进中的推广应用提供了一定的借鉴。     

Compaction of Lunar‐Type Soil

Soil plays an important role in the construction of foundations of roads and buildings. The utilization of soil traditionally involves the compaction of the in‐situ or previously loosened material to achieve a desired strength. The paper reports an initial investigation on the effect of the percentage of fines on the densification and strength of lunar‐soil simulant. The results of vibratory and static compaction tests in the laboratory suggest that the amount of fines should be reduced from the existing 50% that is typical for lunar regolith. The measurement of density and cone resistance of soil mix with only 10% showed large differences when compared to soils with 30% or 50% fines. No attempt has been made to find optimal soil mixes for compaction.     

Geotechnical Properties of JSC-1A Lunar Soil Simulant

For the success of planned missions to the moon in the near future, it is essential to have a thorough understanding of the geotechnical behavior of lunar soil. However, only a limited amount of information is available about geotechnical properties of lunar soils. In addition, the amount of lunar soils brought back to Earth is small. To help the development of new regolith moving machines and vehicles that will be used in future missions, a new lunar soil similant JSC-1A has been developed. A group of conventional geotechnical laboratory tests was conducted to characterize the geotechnical properties of the simulant, such as particle size distribution, maximum and minimum bulk densities, compaction characteristics, shear strength parameters, and compressibility.     

Behavior of Compacted Lunar Simulants Using New Vacuum Triaxial Device

Development and study of mechanical properties of engineering materials from locally available materials in space is a vital endeavor toward establishment of bases on the Moon and other planets. The objectives of this study are to create a lunar simulant locally from a basaltic rock, and to design and develop a new vacuum triaxial test device that can permit testing of compacted lunar simulant under cyclic loading with different levels of initial vacuum. Then, triaxial testing is performed in the device itself without removing the compacted specimen; this is achieved by a special mechanism installed within the device. Preliminary constrained compression and triaxial shear tests are performed to identify effects of initial confinements and vacuums. The results are used to define deformation and strength parameters. At this time, vacuum levels up to 10?4 are possible; subsequent research should involve higher vacuum levels, e.g., 10?14?torr as they occur on the Moon. The research can have significant potential toward development of methodology so as to develop compacted materials for various construction applications, and also toward stress‐strain‐strength testing of lunar simulants with different vacuum levels.     

土石交界隧道爆破开挖数值分析

运用FLAC3D对黑山隧道土石交界段爆破开挖时爆破振动对隧道稳定情况的影响进行了数值分析.采用球面爆破冲击波的方法对爆破开挖进行了数值模拟,根据数值模拟结果提出了安全装药量,最后就其在爆破控制中的应用进行了分析.研究表明隧道爆破开挖过程中,拱顶及两侧拱腰底部发生了明显的应力重分布现象,拱顶土体对爆破振动敏感,易于发生塑性破坏,中部土体也有部分破坏,但并不影响开挖.      

施工方案技术改进在某金矿深孔爆破成井中的应用

深孔爆破施工方法是切割天井快速成井的有效途径,但钻孔偏差是制约深孔爆破成井成功的重要因素。通过对山东某金矿680中段一采场切割天井钻孔偏差及其现场存在的问题进行分析,在原设计方案的基础上对施工方案进行改进。首先提出以炮孔补偿系数、破碎角和自由面系数这3个参数确定补孔位置及炮孔起爆顺序,解决了钻孔偏差问题;其次采用分次爆破和不同爆炸猛度的炸药解决了装药困难及雷管段别不足的问题。第一次爆破采用卷状乳化炸药进行人工装药,炸药猛度高,但装药效率低;第二次爆破采用特制的改性粒状铵油炸药进行机械装药,极大地提高了装药效率,而且爆破产生的有毒有害气体较少。最终作业现场取得良好的爆破效果,证实改进的施工技术方案切实可行,对类似工程具有一定的指导价值。     

金山金矿硬韧性岩巷道掘进炮眼布设和装药量的改进

介绍了该矿传统掘进凿岩爆破方法,详细阐述了该矿硬韧性岩的巷道掘进炮眼布设及装药系数的确定。通过试验,验证了多凿空掏槽眼,减少装药炮孔个数,加大装药系数的方法有利于提高硬韧性岩巷道掘进效能,大幅增强爆破效果。     

Engineering Properties of Lunar Soil Simulant JSC-1A

This study was carried out to assess the tensile and shear strength in lunar soil, and to examine the variation as a function of density and confinement. Geotechnical engineering properties of the lunar soil simulant designated Johnson Space Center Number One-A lunar soil simulant (JSC-1A) have been investigated experimentally. To better understand these soil properties, a variety of conventional and unconventional experiments were conducted on JSC-1A to determine its grain-size distribution, cohesion, friction angle, dilatancy angle, tensile strength, and appropriate low strain elastic constants. These experiments were conducted on JSC-1A at a variety of densities prepared through tamping densification to quantify the response of the soil over a range of conditions. To simulate lunar conditions, the samples were prepared at medium to very high relative densities. Grain-size distribution, shear strength, tensile strength, dilatancy angles, and elasticity modulus of the JSC-1A were compared with lunar soil and other simulants.     

Indigenous Resource Utilization in Design of Advanced Lunar Facility

The most important consideration in the establishment and support of a permanently manned lunar base will be resource utilization. Seven potential lunar construction materials were analyzed with respect to their physical properties, processes, energy requirements, and resource efficiency. Reviewing the advantages and disadvantages of each material led to the selection of basalt as the primary construction material for initial use on a lunar base. The team conceptualized a construction system that combines lunar regolith sintering and casting to make pressurized structures. The design uses a machine that simultaneously excavates and sinters the lunar regolith to create a cylindrical hole. The hole is then enclosed with cast basalt slabs, allowing the volume to be pressurized for use as a living or work environment. Cylinder depths up to 4–6 m in the lunar mare and 10–12 m in the lunar highlands can be achieved. Advantages identified in the construction system include maximum resource utilization, relatively large habitable volumes, interior flexibility, and minimal construction equipment needs. The conclusions of this study indicate that there is significant potential for the use of basalt as a low‐cost alternative to Earth‐based materials. It remains to be determined, during lunar base phasing, whether this construction method should be implemented.     

NAO-1: Lunar Highland Soil Simulant Developed in China

A new lunar highland soil simulant, NAO-1, has been created in National Astronomical Observatories (NAO), Chinese Academy of Sciences. This simulant was produced by gabbro, which includes large quantity of feldspar (An>90). The simulant’s chemical composition, mineralogy, particle-size distribution, density, angle of internal friction, and cohesion have been analyzed and results demonstrated that most characteristics of NAO-1 are similar with lunar highland soil samples. NAO-1 will benefit the scientific and engineering research of lunar soil.     

Martian and Lunar Cold Region Soil Mechanics Considerations

Robotic missions to Mars are listed and significant results of each past mission related to soil engineering are noted. What is known of the Mars environment and surface features that may be of interest to the engineer is summarized. The presumptive engineering properties of soils on the Martian surface are postulated based on expected soil forming mechanisms, the thermal environment found on Mars, and experience from cold region engineering on Earth. The discussion also extends to likely soil characteristics in craters found in the polar regions of the Moon. Experimental results from triaxial testing inert silt (JSC-1 lunar soil simulant) at and near freezing temperatures, with and without water, are also presented. Areas for future investigation and research are suggested.     

Geotechnical Behavior of JSC-1 Lunar Soil Simulant

To facilitate the modeling and simulation of lunar activities and natural processes, various lunar soil simulants have been created. In particular, Johnson Space Center Number One lunar soil simulant (JSC-1) has come into wide use by a variety of investigators. In any physical experiment, the behavioral properties of this simulant will have a profound impact on the results. To better understand these soil properties, a variety of conventional and unconventional experiments were conducted on JSC-1 to determine its friction angle and appropriate low strain elastic constants. These experiments were conducted on JSC-1 at a variety of relative densities to quantify the response of the soil over the range of possible conditions. Further, the samples were prepared through vibratory densification, allowing for a better simulation of probable lunar surface packing arrangements.     

Regolith Mechanics, Dynamics, and Foundations

Due to the differences of the gravitational accelerations of the Earth and lunar environments, geotechnical engineering must be applied differently in the two environments. This study investigates those differences. Of special interest are the static and dynamic behaviors of soil and regolith materials, as well as some foundation systems. The soil and regolith materials are shown to behave in different ways. The regolith material is more sensitive to environmental factors than the Earth material, and may require nonlinear analysis and∕or improved modeling techniques. Also, care must be exercised when designing Earth‐based tests to study lunar‐based systems.     

Geotechnical Properties of NT-LHT-2M Lunar Highland Simulant

Future lunar explorations require a thorough understanding of the geotechnical properties of lunar soils. However, the small amount of lunar soil that was brought back to earth cannot satisfy the needs. A new lunar soil simulant, NU-LHT-2M, has been developed to simulate lunar regolith in the lunar highlands region. It is characterized to help the development of regolith-moving machines and vehicles that will be used in future missions to the moon. The simulant’s particle size distribution, specific gravity, maximum and minimum densities, compaction characteristics, shear strength parameters and compressibility have been studied; and the results are compared with the information about lunar regolith provided in the Lunar Sourcebook.     

Engineering Issues for Early Lunar‐Based Telescopes

A telescope on the Moon is needed for astronomy and can be constructed in this decade or early in the next century. Design for this telescope will be fundamentally different from the design of free‐flying telescopes. Its design will be more like the new Keck telescope being completed on a mountaintop in Hawaii than the Hubble Space Telescope, in low Earth orbit. Success of the lunar‐based telescope will depend on an appropriately engineered structure, a suitable interface (foundation) in the lunar soil, and a carefully thought out construction process. Participation of engineers in identifying and resolving issues for this extraterrestrial engineering and construction project is a natural extension of the traditional engineering role, and will prepare the engineering and construction communities for the subsequent greater challenges associated with basing on the Moon. These communities need to document now the types of data and information that NASA should obtain in the next early lunar missions so that construction on the Moon will be facilitated.     

Raise Boring in Civil and Mining Applications

Drilling and blasting is the traditional method of shaft excavation. This is labor intensive and time consuming. With the advent of machine boring, the RBM, or raise‐boring machine, was developed to increase safety and decrease the cost of shaft construction. Compared to conventional drill‐and‐blast shaft excavation methods, raise boring offers many advantages: (1) Safety; (2) increased productivity; (3) disturbance of the rock unit from its equilibrium state is not as great as when using drilling and blasting methods; (4) excavation crew size is smaller; and (5) resultant bottom‐line reduction in cost of shaft construction.     

MALEO: Modular Assembly in Low Earth Orbit: Alternate Strategy for Lunar Base Development

Modular assembly in low Earth orbit (MALEO) is a new strategy for building an initial operational‐capability lunar habitation base, the main purpose of which is to safely initiate and sustain early lunar base buildup operations. In this strategy the lunar base components are brought up to low Earth orbit (LEO) by the Space Transportation System (STS), and assembled there to form the complete lunar base. Specially designed propulsion systems are then used to transport the MALEO lunar base, complete and intact, all the way to the moon. Upon touchdown on the lunar surface, the MALEO lunar habitation base is operational. The strategy is unlike conventional concepts, which have suggested that the components of the lunar base be launched separately from the Earth and landed one at a time on the moon, where they are assembled by robots and astronauts in extravehicular activity (EVA). The architectural drivers for the MALEO concept are, first, the need to provide an assured safe haven and comfortable working environment for the astronaut crew as safely and as quickly as possible, with the minimum initially risky EVA, and secondly, the maximum exploitation of the evolutionary benefits derived from the assembly and operation of space station Freedom (SSF‐1). Commonality and inheritability from the space station assembly experience is expected to have an advantageous impact on both the space station program as well as the MALEO lunar base.     

预埋PVC管炮孔影响爆破效果浅析

在拆除爆破施工工程中,利用预埋PVC管作为爆破拆除的炮孔,可以有效的节约钻孔时间及成本,但其爆破效果并不能满足预期效果。针对该问题,根据炸药在PVC管中应力波的传播规律,对PVC管弱化爆破效果进行理论分析,掌握管壁材料波阻抗对孔壁初始压力的影响。利用数值模拟软件ANSYS/LS-DYNA及现场试验,将钻孔和PVC管爆破过程进行对比研究,得出使用PVC管时需要额外消耗约10%的炸药,因此根据不断的现场试验,确定使用PVC管时需要增加单孔药量为50g左右。     

基于LS-DYNA的井下中深孔爆破地表震动强度模拟分析

为了研究微差爆破最大段药量和总药量对爆破震动的影响程度,在对某铀矿井下生产爆破进行爆破震动现场测试的基础上,采用LS-DYNA有限元软件分别以最大段药量和总药量作为集中药包进行数值模拟。分析结果表明,震动强度测试值介于最大段药量和总药量数值模拟值之间,最大段药量虽是影响微差爆破震动强度的重要因素,但非决定性因素,微差爆破震动强度与总药量有密切关系;井下生产爆破地表三维震动强度值中,水平径向值相对较小。