To address the problems of material agglomeration caused by unreasonable temperature field in compact screw extruders, an original Heat Break-like Structure (HBS) was introduced to realize accurate zonal control of the temperature field within the barrel. A novel barrel was iteratively designed through temperature field simulation. The temperature gradient across the feeding zone can be linearly adjusted by altering the internal wall thickness and the external wall depth of HBS. After optimization, the overall length of the device was reduced by 30 %, and the temperature difference across feeding zone reached 30.9 degrees C, 6.92 times higher than that of traditional structure. In addition, the PLA material was formed by an iteratively optimized Fused Granulation Fabrication (FGF) barrel. The tensile strength reached 41.67 MPa when the feed temperature was 160 degrees C and the printing temperature was 195 degrees C. However, the tensile strength dropped to 34.25 MPa when the feed temperature was 155 degrees C and the printing temperature was 210 degrees C. The iterative development of this novel compact FGF device eliminates the need for filament preparation, simplifying the manufacturing process, and holds great significance for achieving a low-carbon economy.

在石油钻井、隧道开挖等领域经常遇到关于岩石切削的问题,岩石切削问题的研究成为提高机械开采效率的重要突破口.针对钻井过程中锥形齿切削岩石的塑-脆性破碎机理这一科学问题,以提高钻进效率为最终目的,通过实验测试岩石力学参数和离散单元法(PFC2D)建立了锥形齿平行切削岩石的数值模拟,研究岩石切削过程中在不同切削深度下的切削形貌、切削力、破岩比功等.结果表明:(1)岩屑先产生宏观剪切裂纹形成半脱落岩屑,后于薄弱处发生张拉失效导致岩屑弹出,并且在切削深度较浅时产生小尺寸岩屑,在切削深度较深时产生大尺寸岩屑.(2)研究了不同切削深度下产生岩屑时的切削峰值力,发现与Nishimatsu的峰值力模型更加符合,与切削深度呈线性增长的趋势.(3)切削力的峰值基本对应裂纹的激增,随着切削深度的增加裂纹图中台阶数会随之减少;破岩比功与切削深度在一定范围内呈正相关,并可以根据MSE2D与logd的关系图将切削过程划分出塑性破坏阶段、小碎屑阶段、脆性破坏3个阶段.

随着钻进深度的加深,破碎硬岩地层愈发困难,提高转速成为硬岩地层快速有效破碎的可行方法之一.孕镶金刚石钻头在硬岩层中具有较好的应用效果,常规转速下孕镶钻头与岩石之间相互作用机理较为完善,超高转速下也有相应的应用和研究基础,但碎岩机理尚未完全清晰.为探究常规速度至超高速下单粒金刚石对岩石的切削力和硬岩的破碎变化情况,以孕镶钻头和岩石相互作用界面响应模型为基础,利用ABAQUS软件建立单粒金刚石切削岩石的二维模型,并提出一种近似分析方法,并进一步推导单粒金刚石受力表达式.结果表明:(1)单粒金刚石对岩石的切削作用主要集中在切削具与岩石接触界面的中上部,高速下比常规切削速度下单粒金刚石受切削力减小,且主要作用部位受到切削速度改变的影响.(2)金刚石颗粒作用岩石中存在塑性破坏和脆性破坏且两种破坏模式交替产生,超高速下岩石产生脆性破坏的比例相比于常规切削速度有所增加,且超高速下切削力波动范围更小,岩石破碎所需的能量更少.(3)提出一种孕镶金刚石钻头碎岩响应近似分析方法,将产生碎岩作用的金刚石颗粒等价为具有"刀尖"和"前、后刀面"的切削具进行分析,推导得到单粒金刚石受力表达式,其受力与切削速度、切削深度等因素有关.研究结果可以为提高转速切削硬岩地层的进一步研究及应用提供依据和参考.

2017年以来教育部推进新工科建设,值此背景,岩土钻掘工程学课程作为地质工程专业核心主干课程,教学方法、成绩评定等方面目前存在诸多问题,不利于新工科的发展与人才的培养,急需教学改革.该文阐述岩土钻掘工程学教学目的与要求及课程特色,分析新工科背景下课程教学存在的问题,从教学内容、教学方法、教学平台、教学评价和校企合作等方面进行改革探讨,着力打造一门富有特色的一流新工科课程.

涡轮是钻井行业常用的一种机械结构,通常应用于井下涡轮发电机、涡轮钻具等.随着计算流体力学(CFD)理论与数值求解方法的不断拓展和革新,CFD方法已经成为井下涡轮性能研究的重要手段.目前针对井下涡轮的研究均是静态的.利用Fluent软件,采用滑移网格方法,编写UDF(user defined function)文件对井下涡轮进行动态仿真,研究了外界负载、叶片数量、流量、叶片安装角对井下涡轮水动力性能的影响,并对井下涡轮的启动特性和运动过程进行了分析.结果表明:启动力矩小于负载时,涡轮静止不动;涡轮所受的启动力矩大于负载时,涡轮开始转动.涡轮转动过程中涡轮所受力矩不断减小,而转速、冲击力不断增加.转速稳定时,流体产生的力矩与负载平衡,冲击力稳定.

The carbon and sulfur cycles in coastal wetland sediments are intricately linked. We measured total organic carbon (TOC) and total reduced inorganic sulfur (TRIS) in sulfate-rich wetland sediments at middle and low elevation saltmarshs along the Yancheng coast, China. Results show that the average TOC concentrations (5.01 +/- 2.31 kg C/m(3)) associated with Spartina sediments in mid elevation sites is much higher than that seen in low elevation mudflats (0.65 +/- 0.25 kg C/m(3)). TRIS concentrations in Spartina sediments ranged from 21.7 +/- 11.2 mu mol.cm(-3) to 3.0 +/- 2.0 mu mol.cm(-3). Within the TRIS pool, elemental sulfur (ES) constituted the lowest fraction (3.6% to 31.4%) and chromium reduced sulfur (CRS) and acid volatile sulfur (AVS) fractions were higher particularly at coasts characterized by siltation, ranging from 29.9% to 62.2% and from 28% to 59%, respectively. AVS or CRS contents correlated positively with dissolved iron/SO42- and pH, while no clear relationship was present between the TRIS fractions and the abundance of sulfate reduction genes or between the TRIS fractions and TOC. Massive pyrite was the dominant authigenic pyrite present at all sites. Our results suggest that with sea level rise, prolonged inundation and rapid siltation would increase TRIS (especially AVS) and TOC accumulation concurrently while coastal erosion and strong waves would reduce both TOC and TRIS accumulation but increase the ES proportion due to exposure to aerobic conditions.

针对水介质中压力冲击波在破碎岩石方面的应用,研究高压脉冲放电在泡沫电介质中的放电机理.根据不同电介质的电离特性配比了两种阴阳离子的泡沫电介质,数值模拟分析了在不同电介质环境下高压脉冲放电时的冲击压力变化规律.运用气泡动力学方程分析了气泡在放电过程中的爆破形态,分析了不同放电电压、放电间隙等条件对气泡爆破形态的影响规律.并进行了初步室内实验,验证了泡沫作为电介质实现高压脉冲放电破碎岩石的可行性.由于泡沫可产生空泡效应,能增加爆破效果,而且泡沫在防漏、密封性能要求等方面都优于水介质,具有更广阔的应用前景.

“海洋化学”课程是海洋科学专业本科教学中重要课程,海洋化学知识是培养海洋类人才必备的基础知识之一.笔者借鉴中国地质大学(北京)海洋学院及其他高校的“海洋化学”本科生课程的教学经验,结合中国地质大学(北京)作为地质院校的特色以及海洋学院海洋科学专业地质背景的具体情况,对“海洋化学”课程的教学内容、教学方式和课时分配等做了合理调整,完善了理论教学和实验教学课程体系.

With the theoretical exploration and material performance improvement, high-speed cutting technology has achieved great application in the field of hard material processing. Some researchers have begun to try to apply it to well drilling. To understand the cutting mechanism of PDC cutter under high speed conditions, the process of rock cutting by PDC cutter under high speed condition was simulated by ABAQUS software. High-speed cutting model was researched by temperature rising, stress, energy change and mechanism of chip formation. Through comparative study, it was found that with the increase of cutting speed, the plastic rock breaking method based on crushing began to transform into the brittle failure mode dominated by cutting action. The temperature of the tool surface becomes lower and the surface stress of the tool begins to stabilize. The mechanical specific energy characterizing cutting efficiency continues to decrease. The cutting efficiency is greatly improved. The research results can provide a theoretical basis for further research and field application of high-speed cutting technology.

等离子爆破技术是一种新型爆破技术,其爆破孔的设计对整个爆破效果及爆破效率起着决定性的作用.本文基于ANSYS/LS-DYNA建立了爆破孔的有限元模型,并对爆炸荷载作用下掏槽孔孔壁压力及其破碎区进行了数值模拟.研究结果表明,爆破时畸变能的变化自始至终都基本呈椭圆形,孔径越小,积累的能量越大,对岩体破坏越大;孔深长度越短,能量积聚空间越小,爆破对岩体造成的破坏越大;孔深长度的改变对下部岩体影响较小,对中部岩体影响较大.此外由于爆炸实验多为破坏性实验,很难进行原型试验,因此使用数值模拟方法研究爆破孔的结构是可行的,可以作为实际工程的参考.

Geophysical technology is a main technical tool of exploration for deep mineral resources. For a long time, China's technology and equipment in this industry rely heavily on imports, the Chinese made exploration techniques, whether instruments or equipment, and methods or software, cannot meet the growing demand in the country. To tackle this problem, a major project "Exploration Techniques for Deep Mineral Resources" was initiated as part of the National 863 Program in the 12th Five-year Plan of China. It focused on increasing the exploration depth, precision, resolution and the anti-interference capability of exploration and developing technology and equipment of high-precision gravity-magnetic, electrical and electromagnetic, seismic, drilling and down-hole exploration. After 4 years of efforts, more than 10 key technologies have been broken through, such as the high-precision microgravity sensor, cesium optical pump magnetic field sensor and broadband induction electromagnetic sensor; 18 sets of exploration geophysical instruments and equipment have been developed, improved and upgraded respectively, including ground high-precision digital gravimeters, proton magnetometers, high-power pseudo-random wide-field electromagnetic detection systems, and distributed multiparameter electromagnetic detection systems. Meanwhile, 20 exploration geophysical data processing and inversion methods have been innovated and improved; 2 sets of large-scale software systems suitable for data processing and interpretation of metallic deposits and 8 sets of other special software systems have been developed and improved. These achievements have greatly raised the technical level of geophysical exploration in China. This paper aims to introduce primary achievements of this project. Firstly, it reviews the development history of geophysical exploration technology in China, and then presents main achievements and progress of the major project of "Deep Mineral Resources Exploration Technology". Finally, we give our views and suggestions on the further development of geophysical exploration technology in China.

环境质量同生活品质密切相关,环境取样钻机在环境质量检测中扮演着不可或缺的角色.本文综述了直推式、声频振动式和回转式环境取样钻机的工作原理及发展历程,总结了国内外钻机在智能化、结构紧凑程度和外观造型上的差距,提出了环境取样钻机的关键能力,包括移动能力、钻进能力和样品保真能力,指出了环境取样钻机将朝着动力采用清洁能源、自动分析样品和适应多种场合的方向发展.

辐射井作为城市地下水供水构筑物和盐碱地改良的集水设施,凭借单井出水量大、水质稳定及控制面积大等特点被广泛应用.本文对传统辐射井施工方案进行了调研,并分析总结出传统集水井和辐射孔施工过程中存在施工安全性低、钻进效率慢且钻孔质量差等问题,提出了以旋挖钻进的方式施工辐射井中的集水井,以水平定向钻进的方式施工辐射孔的方案.通过现场实验,发现此方案能有效解决传统方案中存在的问题,进一步研究之后值得推广.

Due to the complexity of marine geotechnical engineering, the harsh operating environments, loose subsea soils, and high water contents, it is extremely difficult to obtain soil samples while maintaining the in situ conditions in offshore areas. The engineering properties of submarine soil layers in the Bohai Sea, China, were investigated in this work. The Wison-APB borehole wireline piezocone penetration test (CPTU) system was used to conduct direct measurements of the cone tip resistance, sleeve friction, and pore pressure. The soil classification and the related soil properties, such as the undrained shear strength, sensitivity and overconsolidation ratio, shear strength profile at the investigation depths, and the single pile foundation bearing capacity, were estimated. Laboratory tests were also conducted in this work. The CPT test results show that there were large differences between the results of the CPT tests (S-u) and the laboratory experimental results, which may be due to the compact silt and hard clay interbeds in some layers. The soil classification was determined according to the previous literature. The laboratory test results of the undrained shear strength, clay sensitivity, and the OCR match the CPT test results best when the parameters N-kt, N-s, and k are 15, 6, and 0.3, respectively. The final determination of the ultimate pile capacity depends on the soil's mechanical properties and the pile type and design. The effects of wave surge and wind loading should also be taken into account in offshore engineering.

粉细砂地层加固处理工作一直是工程界研究的重点课题,采用传统注浆工法很难达到预期效果.针对此种情况,近年来提出振动注浆法,然而目前的振动注浆模拟试验与实际工况有较大出入,故创新设计了试验装置,可以满足自由调控振动频率,且振动效果与实际工况接近.通过室内静压注浆试验及声频振动注浆试验,对比注浆效果,得出以下结论:压力相同条件下,相比静压注浆,振动注浆可以有效增大注浆量且加固效果更优;振动频率的适当增加可以有效加快注浆速度,增大注浆量,这对于工期紧张的工程具有一定的实际意义,但频率过高并非完全有利于注浆效果,要根据实际工况选择最优注浆频率;高频振动下,振动时间的延长对注浆效果的增益较小.

When exploiting the deep resources, the surrounding rock readily undergoes the hole shrinkage, borehole collapse, and loss of circulation under high temperature and high pressure. A series of experiments were conducted to discuss the compressional wave velocity, triaxial strength, and permeability of granite cored from 3500 meters borehole under high temperature and three-dimensional stress. In light of the coupling of temperature, fluid, and stress, we get the thermo-fluid-solid model and governing equation. ANSYS-APDL was also used to stimulate the temperature influence on elastic modulus, Poisson ratio, uniaxial compressive strength, and permeability. In light of the results, we establish a temperature-fluid-stress model to illustrate the granite’s stability. The compressional wave velocity and elastic modulus, decrease as the temperature rises, while poisson ratio and permeability of granite increase. The threshold pressure and temperature are 15 MPa and 200°C, respectively. The temperature affects the fracture pressure more than the collapse pressure, but both parameters rise with the increase of temperature. The coupling of thermo-fluid-solid, greatly impacting the borehole stability, proves to be a good method to analyze similar problems of other formations.

The Downhole motor is a kind of important rotary or percussive power drilling tool driven by high pressure mud. Drilling using downhole motor can reduce the energy consumption caused by the friction between long drill string and borehole, and reduce drill pipe wear. In this paper, some important drilling simulation experimental devices around the world have been studied, especially, two kind of drilling simulation experimental devices, the conventional bottom hole experimental device and high temperature and high pressure experimental devices have been analyzed respectively. At home and abroad, the typical drilling simulation devices include ZM-35, LST-10, LMT-I, M150, and Terra Tek, etc.. The characters, structures, principles and experimental methods of these typical simulation devices had been introduced in detail, which provides a reference for developing downhole motor testing and drilling process testing.

Mangroves are an important affecter of atmospheric CO2 level via sequestrating carbon and trapping sediments. However, their sequestrating effectiveness varies with vegetation development and sedimentation processes under site-specific hydrogeomorphic settings. In order to detect the determinants of organic carbon sequestration, this study investigated four mangrove fringing locations along the coast of the Leizhou Peninsula. Surface and core sediment samples were collected from these sites and analyzed for grain-size distribution, sedimentary organic carbon content (SOCC) and stable isotope signature (δ13Corg). It is found that a significantly higher concentration and density of organic carbon were preserved in the interior surface sediments regardless of location or surface grain size distribution. The sedimentary environments, as indicated by core sediment analysis, are controlled under low-to moderately low-energy conditions. Fluvial action on these sedimentary environments decreases from the river dominated site to the tide dominated site. The more stable energy condition favored both sediment and organic carbon accumulation in the mudflat subzone. However, as revealed by δ13C signature, sedimentary organic carbon of the core samples from the four sites was dominantly derived from suspended particulate matter except the tide-dominated offshore core. Whereby, we conclude that vegetation provided control on the surface sedimentary organic carbon distribution via its influence onmangrove debris input and fluid energy condition over the intertidal surface, while hydrogeomorphology determined the long-term organic carbon burial via its impact on the local sedimentation accretion rate and the proportion of autogenous organic carbon sequestration.

海洋化学是海洋科学的一门基础学科,通过理论与实验教学,培养学生运用化学的思维和理论手段,尝试解决发生在海洋环境中的化学问题能力。该文阐述了我校《海洋化学》课程的建设过程与改革建议。

According to the granite formations of deep wells and ultra-deep drilling,through the measurement of the longitudinal wave velocity after the granite heating and conventional tri-axial compression tests,and based on the experimental results,the study is made on the longitudinal wave velocities of granite by different temperatures heating and macro mechanical properties under tri-axial compression stat. The analysis is made on the relationship between the granite longitudinal wave velocity,peak stress,elastic modulus,peak strain and the temperature; at the same time,the granite macroscopic failure form under the condition of tri-axial compression are summarized. The results show that,after heating and cooling,granite longitudinal wave velocity is decreasing with increasing temperature; meanwhile,under a constant confining pressure,when the temperature changes from 20℃ to 200℃,the peak stress,elastic modulus,peak strain tended to increase with the temperature increasing,but when the temperature changes from 200℃ to 400℃,these mechanical parameters is decreasing. Temperatures can make the water content of rock gradually decreases,and because of different thermal expansion of rock internal mineral compositions,the additional thermal stress inside the rocks is generated,thereby the initial crack inside the rock will have propagation and coalescence or new cracks generate to affect the stability of the borehole wall and the surrounding rock.