Analysis of Passive Limited Supporting Force of Curved Shield Tunnel Excavation FaceEI北大核心

Research purposes: In the construction process of curved shield tunnels, the force of excavation face is extremely complex and the stability is difficult to control, so it is very likely that the thrust of the jack will cause uplift of the soil in front because of passive failure. Taking the sand strata as an example, this paper established a combination model of "inverted ladder-wedge prism" to reveal that the soil in front of the excavation face of curved shield tunnels uplifts up because of passive failure based on the silo theory and limit equilibrium method, and deduced the calculation method of passive limited supporting force for curved tunnels. Then, we confirmed the accuracy and reliability of this model and calculation method through programing and simulating. Research conclusions:(1) The passive limited supporting force increases with the increase of buried depth and internal friction angle, and the growth rate gradually increases. (2) When the radius of the line is less than 200 m and the internal friction angle is more than 25 degrees, the passive limited supporting force is very sensitive to the curvature radius, and when the radius is more than 800 m, the passive limited supporting force is almost no difference with straight tunnels. (3) The numerical results indicate that the numerical solution is consistent with the theoretical solution and the difference is quite small. (4) The research results can provide theoretical basis for determining the passive limited supporting force in the constructions of similar curved shield tunnels especially small turn radius shield tunnels. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the Cause and Influential Factors of Tunnel Lining Cracking of Side Wall in Seasonally-frozen RegionsEI北大核心

Research purposes: In recent years, tunnel diseases like lining cracking and water leaking during spring thawing period, caused by frost heaving of surrounding rock, have occasionally occurred in high-latitude seasonally-frozen regions of northwest China and northeast China, which has seriously affected the tunnel structure and operation safety. Taking several railway tunnels in northwest China as an example, this paper investigates the cause and main influencing factors of longitudinal cracking of side wall in winter in seasonal frozen soil area by means of field test, laboratory experiment and numerical simulation. Research conclusions:(1) When the water content of surrounding rock of tunnel built in strongly-weathered sandstone is 12.3% and the frozen depth of surrounding rock is up to 60 cm, the maximum tensile stress of side walls is 2.28 MPa, which is larger than the ultimate tensile strength of C30 concrete, then the horizontal lining cracking will appear on side walls under the effect of continuous negative temperature in winter. If the lining bears part of the surrounding rock load, the longitudinal cracking degree of the side wall will increase. (2) Under the effect of frost heaving loads, the cracking of tunnel lining has its own characteristics of symmetry, seasonality and accumulation, etc. The cracks appear in winter and distribute in the middle of side walls. As the temperature is rising, the crack begins to shrink. (3) The frozen circle thickness and water content of surrounding rock should be used as main indicators during the process of calculation of frost heaving loads of surrounding rock in seasonally-frozen regions. (4) The research results can be used for reference in tunnel design, operation and maintenance in seasonal frozen soil area. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

模腔注射填充的全矢量显式算法

为满足注射成形模拟工业应用的实际需要，基于已有的模拟注填充显式算法，提出并实现了一种新的全矢量化显式算法，对于各类注射填充的模拟问题，此算法避免了压力场的全局求解，矩阵操作仅在单元一级进行，通过反馈修正，各时间增量步满足不可压缩条件，由于避免了所有的全局耦合求解，计算代价与节点的自由度近似成正比，可实现填充模拟过程的高效运算，容易实现并行计算，通过新算法的填充模拟结果与MINI单元的三维模拟结果比较，证实了该算法的有效性。     

轨道车辆直流牵引电机噪声的分析与研究

本文在城市轨道车辆牵引电机噪声测试的基础上,分析了牵引电机噪声的产生机理和频率分布以及对室内外环境的影响和传播途径。最后提出了牵引电机的降噪措施。     

LOSS OF NUCLEUS BASALIS MAGNOCELLULARIS，BUT NOT SEPTAL，CHOLINERGIC NEURONS CORRELATES WITH PASSIVE AVOIDANCE IMPAIRMENT IN RA

ＬＯＳＳＯＦＮＵＣＬＥＵＳＢＡＳＡＬＩＳＭＡＧＮＯＣＥＬＬＵＬＡＲＩＳ，ＢＵＴＮＯＴＳＥＰＴＡＬ，ＣＨＯＬＩＮＥＲＧＩＣＮＥＵＲＯＮＳ　ＣＯＲＲＥＬＡＴＥＳＷＩＴＨＰＡＳＳＩＶＥＡＶＯＩＤＡＮＣＥＩＭＰＡＩＲＭＥＮＴＩＮＲＡＴＳＴＲＥＡＴＥＤ　ＷＩＴ...     

FRP材料在海港工程中的应用

海工建筑物中的钢筋锈蚀已成为全世界普遍关注并日益突出的一大问题。FRP筋因其优越的防腐性、抗拉强度高、重量轻、总体使用成本低等特点,成为海工结构中钢筋的理想替代品。文中在分析有关资料的基础上,综述了国内外对FRP材料及其在土木工程中应用的研究,并结合海港码头结构的特点,提出FRP材料在海港工程应用中的关键技术,展望FRP应用前景。     

THE EFFECT OF VITAMIN C INTAKE ON GLYCOHEMOGLOBIN MEASUREMENTS

ＴＨＥＥＦＦＥＣＴＯＦＶＩＴＡＭＩＮＣＩＮＴＡＫＥＯＮＧＬＹＣＯＨＥＭＯＧＬＯＢＩＮＭＥＡＳＵＲＥＭＥＮＴＳＦａｎｇＺｈｉｙｕ；ＳｕＭｉｎｇ，Ｒ．Ｒ．Ｌｉｔｔｌｅ，Ｈ．Ｍ．Ｗｉｅｄｍｅｙｅｒ，Ｄ．Ｅ．Ｇｏｌｄｓｔｅｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｉ...     

船闸闸室墙表面修复砂浆物理力学性能试验研究

对丙乳砂浆、硅粉砂浆、高强砂浆、聚丙烯纤维高强砂浆及玄武岩纤维高强砂浆5种船闸闸室墙表面修复材料进行了一系列物理力学性能试验。研究结果表明：丙乳明显降低了砂浆的抗压、抗折尤其是抗压强度,但能有效改善砂浆的早期抗干缩能力及增强砂浆韧性：由于硅粉微粒的填充作用及火山灰反应硅粉砂浆具有优良的力学性能,其28d抗压、抗折和抗拉强度分别为分别为85．9MPa、15．93MPa和5．732MPa,能承受的抗弯荷载也较大,为5.3kN,但其塑性收缩大且韧性不强;聚丙烯纤维和玄武岩纤维高强砂浆具有较高的力学性能,同时纤维的加入能有效改善砂浆的早期抗干缩能力．显著增加砂浆的断裂挠度和韧性从而提高砂浆抵抗变形开裂的能力。     

THE NEURONS DOUBLE-LABELLED BY SEROTONIN AND GLUTAMATE-IMMUNOREACTIVITY IN

ＴＨＥＮＥＵＲＯＮＳＤＯＵＢＬＥ－ＬＡＢＥＬＬＥＤＢＹＳＥＲＯＴＯＮＩＮＡＮＤＧＬＵＴＡＭＡＴＥ－ＩＭＭＵＮＯＲＥＡＣＴＩＶＩＴＹＩＮＭＥＤＵＬＬＡＲＹＲＡＰＨＥＮＵＣＬＥＩＰＲＯＪＥＣＴＩＮＧＴＯＴＨＥＣＥＲＥＢＥＬＬＡＲＣＯＲＴＥＸＯＦＴＨＥＫＩ...     

Power control strategy for preventing thermal failure of passively cooled automotive battery packs

Safety mechanism is required for an automotive battery pack to prevent thermal failure which could lead to catastrophic events. Passively cooled battery packs can prevent thermal failure by conducting adaptive control of battery power without any external cooling device. The key to this power control is how to secure battery safety while minimizing energy loss. This paper proposes a novel, adaptive power control strategy for automotive passive-cooling battery packs. Four different cases with electrochemical battery model are simulated and compared to each other according to a city driving profile. Driving simulation result confirmed that the present power control algorithm is an effective solution for preventing thermal failure along with improving energy efficiency of automotive battery packs.