薄壁型钢管/胶合竹板复合柱抗震性能试验

对9根带约束拉杆的方形薄壁型钢管/胶合竹板复合空芯柱(SBCCB)试件进行低周反复拟静力测试,考察SBCCB的破坏过程和形态,分析试件的长细比、胶合竹净横截面面积、截面组合方式对其受力和抗震性能影响。结果表明:SBCCB破坏形态主要为柱脚胶合面的开裂破坏和胶合竹板断裂破坏,截面组合方式对其破坏模式有显著影响。SBCCB试件有较好的弹性变形能力和抗震耗能性能,增大复合柱截面尺寸和长细比能改善抗震性能;约束拉杆有效保证了试件的整体性,抑制基体开胶破坏,间接提高了抗震性能。     

青海湖嗜盐微生物筛选分离与生长特性

为全面获得青海湖嗜盐菌种质资源,构建种群系统发育树和确定种群进化定位.采用高盐选择性培养基筛选,分离从20份青海湖水样中获得35株青海湖嗜盐微生物.耐盐梯度实验表明:水体中以中度嗜盐菌为主,约占62.85%,轻度嗜盐菌约占22.85%,非嗜盐菌与耐盐菌约占14.28%.青海湖中度嗜盐微生物能在10～45℃,pH 5.5～11.0的范围内生长,与地区盐碱化环境相关,具有嗜盐兼嗜碱微生物的特性.     

三峡水库156m蓄水前后澎溪河回水区藻类多样性变化特征

为了解156 m蓄水前后三峡水库次级河流藻类多样性变化特征,对2007年7月至2008年1月澎溪河回水区的藻类种群结构的变化进行连续监测.基于三峡水库水位调度特点,将监测期划分为蓄水前、中、后三个时段,即7-9月、10月、11月至翌年1月,应用Shannon-Weaver多样性指数H’对藻类多样性进行评价,通过Connell中度扰动假说理论结合优势藻种探讨蓄水过程水动力变化及藻类多样性的变化特征.结果表明:2007年7-9月蓄水前H’均值为3.466±0.317,10月蓄水期则降为3.246±0.338,而11月蓄水后高水位阶段H’均值上升为3.431±0.352.蓄水前澎溪河回水区具有河流型特征,流量与降雨作为主要的物理扰动因子影响水体扰动强度,进而引起多样性变化.10月蓄水期间水位突升、流量骤降导致水体扰动强度加剧,较蓄水前藻类多样性下降.自11月蓄水后的高水位阶段,降雨较小、流量趋于稳定,水体扰动降低,多样性回升并维持在相对稳定的状态.     

THE PRELIMINARY STUDY ON THE SEISMOGENIC STRUCTURE OF THE HUTUBI MS6.2 EARTHQUAKE

Based on the phase report of Xinjiang Seismic Network, the Hutubi M_S6.2 earthquake sequence M_L ≥ 1.0 was relocated by the HypoDD method. The results show that the aftershocks were distributed along NE and NW direction. The aftershocks were in the depths of 5~15km. In addition, by using the digital waveforms of Xinjiang Seismic Network, the best double-couple focal mechanism of the main shock and some aftershocks of M_S ≥ 3.8 were determined by the CAP method. Based on the above studies, the source depth, focal mechanism and aftershock distribution of the Hutubi M_S6.2 earthquake were analyzed and the seismogenic structure was discussed. The nodal plane parameters of the best double-couple focal mechanism are strike 144°, dip 26°, rake 118°, and strike 293°, dip 67°, rake 77°, respectively. The moment magnitude M_W is about 5.9, with centroid depth of 15.2km. These show that the main shock was a thrust type. Most focal mechanism solutions of the aftershocks were shown as a thrust type, which are similar to the main shock. It is speculated that the possible seismogenic fault of this earthquake is the Huorgosi-Manas-Tugulu Fault.     

2018年9月12日陕西宁强5.3级地震震害特征及发震构造背景

2018年9月12日在陕西省汉中市宁强县与四川省广元市交界处(32.75°N,105.69°E)发生5.3级地震。现场调查结果表明,此次地震最高烈度为Ⅵ(6)度。Ⅵ度区等震线呈椭圆状,其长轴呈北东走向,主要涉及到陕西省和四川省广元市的13个乡镇。部分震区房屋建筑出现轻微破坏现象。这次地震的发震断层是龙门山断裂带中的青川断裂。     

EARTHQUAKE LOCATION AND VELOCITY STRUCTURE IN YIBIN AREA,SICHUAN

Small earthquakes have been recorded in Yibin area, Sichuan Province since 1970, the frequency and intensity of seismicity have shown an increasing trend in recent ten years, and the earthquakes are distributed mainly in Changning, Gongxian and Junlian areas. Based on the seismic data from January 2008 to May 2015 recorded by Sichuan and Yunnan regional networks and Yibin local network, seismicity analysis, precise location and velocity structure inversion for earthquakes in Yibin area are carried out, the three-dimensional spatial distribution of seismic activity and the velocity structure at different depths in this region are investigated, trying to analyze the seismic activity law and seismogenic mechanism in Yibin area. The earthquake relocation result shows that the spatial cluster distribution of earthquakes is more obvious in Yinbin area, the earthquakes are concentrated in Changning-Gongxian and Gongxian-Junlian regions. The seismic activity presents two dominant directions of NW and NE in Changning-Gongxian region, and shows asymmetric conjugate distribution, the long axes of NW-trending and NE-trending seismic concentration area are about 30km and 12km respectively, and the short axes are about 5km. There is a seismic sparse segment near Gongxian, the frequency and intensity of seismicity in the southeast side are obviously higher than that in the northwest side, and the earthquakes with larger magnitude are relatively deep, the focal depth is gradually shallower with the distance away from Gongxian. Seismic activity is sparse in the west and dense in the east in Gongxian-Junlian region, the predominant direction of earthquakes in the seismic dense area of the eastern segment is NE. Seismic activity extends in opposite direction in the easternmost part of the two earthquake concentrated area. The P-wave velocity structure at different depths in the study area is obtained using joint inversion method of source and velocity structure. In view of the predominant focal depth in this region, this paper mainly analyzes the velocity structure of the upper crust within 10km. Within this study area, the P-wave velocity of earthquake concentration areas is relatively high within 10km of the predominant focal depth, especially in the northwest of Gongxian and eastern Junlian area, the P-wave velocity on the southeast of Gongxian increases gradually with depth, especially at 6km depth. These high-velocity zones are generally related to brittle and hard rocks, where the stress is often concentrated. Comparing earthquake distribution and velocity structure, seismic activity in this area mainly occurs in high-low velocity transition areas, the inhomogeneity of velocity structure may be one of the factors controlling earthquake distribution. The transition zone of high and low velocity anomalies is not only the place where stress concentrates, but also the place where the medium is relatively fragile, such environment has the medium condition of accumulating a large amount of strain energy and is prone to fracture and release stress.     

顾及观测质量的多系统融合PPP三维凸包选星算法

从卫星空间构型出发,构建多系统融合PPP的三维凸包选星算法;为进一步改善多系统融合PPP的定位性能,提出顾及观测质量的三维凸包选星思路;最后结合实测数据验证并分析各自的选星效果和定位性能。     

Studies on Factors Influencing Hydrodynamic Characteristics of Plates Used in Artificial Reefs

As a simplified model of artificial reefs, a series of plate models punched with square or circular openings are designed to investigate the effects of openings on the hydrodynamic characteristics of artificial reefs. The models are grouped by various opening numbers and opening-area ratios. They are physically tested in a water flume or used in the numerical simulation to obtain the drag force in the uniform flow with different speeds. The simulation results are found in good agreement with the experimental measurements. By the non-dimensional analysis, the drag coefficient specified to each model is achieved and the effects of openings are examined. It is found that the key factor affecting the drag coefficient is the open-area ratio. Generally, the drag coefficient is a linear function of the open area ratio with a minus slope. The empirical formulae for the square and circular openings respectively are deduced by means of the multiple regression analysis based on the measured and numerical data. They will be good references for the design of new artificial reefs. As a result of numerical simulation, the vorticity contours and pressure distribution are also presented in this work to better understand the hydrodynamic characteristics of different models.     

黑河“97”分水方案适应性分析

黑河"97"分水方案自2000年实施以来,流入下游水量明显增加,缓解了下游生态环境恶化趋势,但在丰水年难以完成分水指标,其适应性受到各方关注。本文在分析"97"分水方案的技术特点及背景条件变化对分水方案适应性影响的基础上,通过构建黑河水资源配置模拟模型,对分水方案在不同需水条件和黄藏寺水库建成运行后长系列年(1958-2012年)实施情况进行了模拟,分析评价了黑河"97"分水方案的适应性。研究表明,由于分水方案制定和实施前后黑河经济社会、水系连通性等背景条件发生了较大变化,在现状工程和需水条件下,不能完成"97"分水方案的分水要求;在中游退耕至2000年水平和黄藏寺水库建成的情况下,虽然可以完成"97"分水方案的分水要求,但仍存在地下水超采情况,因此,基于20世纪80年代中期黑河经济社会和1955-1986年水文条件的"97"分水方案与黑河流域现状存在一定的不适应性。     

土地利用转型与乡村转型发展耦合研究进展及展望

城乡转型发展进程中,土地利用转型与乡村转型发展是乡村地域系统演变的重要特征,系统开展土地利用转型与乡村转型发展的耦合过程及互动机理研究有利于揭示乡村演变的内在规律。土地利用转型研究为深化乡村地理学研究提供了一个全新的视角。深入开展土地利用转型与乡村转型发展耦合研究可为因地制宜制定乡村发展战略,适时调控乡村土地利用政策提供参考。当前,针对土地利用转型与乡村转型发展耦合研究的理论体系、技术方法、内在机理等尚缺乏系统的建构,基于耦合研究优化乡村转型重构的路径仍显不足。为此,本文在系统梳理土地利用转型与乡村转型发展耦合研究进展的基础上,从耦合理论分析框架、“格局—过程”耦合和梯度分异导向的耦合三个层面提出针对性的研究展望,以期丰富乡村地理学研究内容。