INVESTIGATION TO LANDSLIDES TRIGGERED BY THE 1856 QIANJIANG-XIANFENG(DALUBA)EARTHQUAKE AND THEIR GENERATION MECHANISMS

On 10 June 1856, an M61/4 earthquake occurred between Qianjiang, Chongqin and Xianfeng, Hubei, resulting in severe geologic hazard including a series of large-scale landslides. Based on previous work, combining field investigations and remote sensing imagery, we have mapped the locations of three landslides triggered by this event, dominated by slumps. Our field work included observations to every failure slopes and occurrence, lithology and joints of rocks in the surroundings. We also employed an unmanned air plane to take pictures of the study area, yielding high-resolution DEM and DOM data which permit to generate terrain contours with a 2m interval. With these field investigations, we have described the sizes and forms of each slump mass in detail, and studied their generation mechanisms. Our research suggests the following natural conditions are responsible for these seismic landslides. 1)In a tectonic stress field characterized by NW-SE directed principal compressive stress, the slopes received a seismic acceleration from NW to SE in a short time. 2)Strata dip in a direction consistent with the seismic motion, thus the slope was easy to slide along stratum interfaces. 3)The two sets of joints existing in rocks experienced long-term weathering, resulting in connection of partial structural planes and destruction to the intactness of rock bodies.     

Numerical investigation of the resistance of precast RC pinned beam‐to‐column connections under shear loading

In precast technology, the effective design and construction are related to the behaviour of the connections between the structural members in order to cater for all service, environmental and earthquake load conditions. Therefore, the design and detailing of the connections should be undertaken consistently and with awareness of the desired structural response. In the research presented herein, an analytical expression is proposed for the prediction of the resistance of precast pinned connections under shear monotonic and cyclic loading. The proposed formula addresses the case where the failure of the connection occurs with simultaneous flexural failure of the dowel and compression failure of the concrete around the dowel, expected to occur either when (i) adequate concrete cover of the dowels is provided (d > 6 D) or (ii) adequate confining reinforcement (as defined in the article) is foreseen around the dowels in the case of small concrete covers (d < 6 D). The expression is calibrated against available experimental data and numerical results derived from a nonlinear numerical investigation. Emphasis is given to identifying the effect of several parameters on the horizontal shear resistance of the connection such as: the number and diameter of the dowels; the strength of materials (concrete, grout, steel); the concrete cover of the dowels; the thickness of the elastomeric pad; the type of shear loading (monotonic or cyclic); the pre‐existing axial stress in the dowels; and the rotation of the joint. In addition, recommendations for the design of precast pinned beam‐to‐column connections are given, especially when the connections are utilised in earthquake resistant structures. Copyright © 2017 John Wiley & Sons, Ltd.     

萧山-球川断裂富阳—建德段第四纪活动性研究

萧山-球川断裂是浙江地区1条大规模的北东向断裂,在该断裂附近曾发生过多次破坏性地震。本文通过地质调查、电法勘探和探槽开挖等方法,对萧山-球川断裂富阳—建德段第四纪活动性进行了研究。萧山-球川断裂富阳—建德段的遥感影像线性特征清楚,对地貌的控制作用较为明显,对山前的第四系发育有明显影响。通过对断裂露头剖面的分析,认为萧山-球川断裂富阳—建德段活动性质以走滑兼具逆冲为主。通过本次开挖的富阳峙山村探槽,结合ESR年龄测定,判定该断裂在第四纪早、中期有过活动,但未断错上覆中更新统上部地层,其最新活动时代为早、中更新世。     

Disaster Investigation for August 20th, 2019 Sanya M4.2 Earthquake in Hainan, China

On August 20^th, 2019, a M4.2 earthquake occurred near Zhanan and Lixin Village, Tianya District, Sanya City, Hainan Province. We conduct field investigations in the vicinity of the epicenter which includes 25 natural villages based on the data provided by local government and finally complete the map of the earthquake intensity. Through the analysis of the houses and cracks in the earthquake area, the structure types and crack characteristics of the houses are basically unveiled. Furthermore, suggestions for earthquake disaster reduction in study area are obtained from the investigation.     

Ring permeametry: design,operation and error analysis

Assessment of slope stability, soil management or contaminant transport problems usually requires numerous, yet accurate point measurements of permeability. This technical note describes a new method for the rapid field assessment of permeability in near-surface soils or unconsolidated sediments. The procedure is known as ‘ring permeametry’ and is an ex situ core-based method giving measurements which can be guaranteed to be stratum-specific, unlike measurements from some in situ techniques. The potential sources of precision and bias error within the method are quantified and their effect on the uncertainty of permeability estimates is illustrated. © 1997 John Wiley & Sons, Ltd.     

地震观测环境调查评估及监控

地震观测数据的准确性和连续性,不仅取决于观测仪器、观测方法和观测技术水平,在很大程度上还依赖于良好的地震观测环境。客观、全面地对地震台站的观测环境进行调查评估,并建立地震观测环境监控体系,对于观测数据的质量控制、地震预报水平的提高和地震行政执法均具有重要意义。     

太湖软土区基坑事故原因调查与分析

基坑安全是基坑施工的关键问题,基坑安全的关联因素多种多样,搞清这些关联因素对基坑的影响特征对基坑科学的发展具有重要的现实意义,通过对环太湖流域(笔者称之为太湖软土区)各类基坑事故的调查分析,初步摸清了太湖软土区基坑安全的关联因素以及这些关联因素对基坑的影响特点,提出了确保基坑安全的一些关键技术措施,为太湖软土区基坑工程的科学设计与施工提供了基础依据,介绍了环太湖流域的自然地理特征、地层结构、岩土物理力学性质、水文地质特征和岩溶特征等基本背景资料,给出了工程实例。     

东阿岩溶水源地水资源评价

本文结合工程实例,介绍了岩溶水源地勘探方法.即通过地面调查、物探、钻探、大流量单、群孔抽水试验以及地面物探等综合勘探评价手段,查清了水源地水文地质条件.获取了该区域水资源计算的有关参数,为岩溶水源地水资评价提供了有价值的借鉴.     

清江流域旅游资源分布规律及成因

通过对清江流域复杂的自然条件和环境的概括,说明了该地区丰富多彩的自然和人旅游资源形成的根本原因,以该地区最具特色的自然景观－地质地貌景观为主要研究对象,阐述了地质过程、地貌演化是该地区其他自然旅游景观形成、演化的主要动力和控制因素。同时,也强调了自然界的时空演进对人文景观形成和分布的重要控制作用。     

高精度人工地震波层析成像技术勘探地下构造

应用人工爆破地震波层析成像方法勘探地下速度结构。在海域、山地多种地质条件下进行了地震波层析成像方法定量勘探研究。依勘探目标体而异,通过设计震源频率、震源和观测仪器布局,提高观测分辨率,实现定量高精度速度结构勘探研究。勘探最大深度可达Moho界面;山地最高分辨率可达3 m。结果显示了该方法在近海区域和山区不同地质条件的适用性及不同勘探深度与勘探精度的实用性。在日本九州近海地域勘测中,同时使用了反射与折射2种走时资料,可以同时改善水平及垂向的分辨率。成像图显示了地下结构详细特征,如任意斜向的凹凸形状,或高角度逆冲错断构造,分辨率达到10 m。同时显示出这些复杂几何体的埋藏深度。结果表明,诸如地下断层形状,资源矿藏储舱结构异常体的复杂几何形状,都可期望在层析成像技术的勘探分辨能力之内。它对于地下结构研究,矿产资源勘探,工程环境地质研究都有重要意义。结果也显示了成像方法的运算收敛速度和计算稳定性在结构勘探中是适用的。