基于IBIS-L的某黄土高填方边坡支护结构变形特征

直立式填方支护在建筑、机场、公路、铁路、矿山等大型基础设施建设项目中的作用不可或缺,但黄土地区边坡支护结构易出现桩基沉降、桩体弯曲、桩板墙开裂的现象。为进一步定量分析其变形特征,采用地形微变监测仪（IBIS-L）进行全天候不间断监测,通过对采集的点面数据进行研究,结果表明：1）支护结构变形总体上具有明显的区域性差异,近15 d的最大变形量为26.6 mm;2）对象监测点位移呈间隔24 h"波浪形"增长规律,且无收敛趋势,极可能导致边坡整体失稳;3）结合温度监测,以监测点Pix8为例,理论计算结果与监测数据相吻合,揭示了s-t曲线呈"波浪形"增长的原因,得出大体积混凝土在大气温度场条件下的变形具有"滞后效应"的响应特征。     

降雨诱发填方路堤边坡变形机制物理模拟研究

填方路堤变形失稳是西部山区工程建设的常见问题。重庆某高速公路边坡为典型的堆载条件下降雨诱发型滑坡,填方堆载后,填方边坡在连续降雨条件下,沿基岩之上的软弱面产生滑动破坏。定性分析认为,降雨在滑坡形成中起着关键作用,为了研究填方边坡在降雨条件下的变形破坏机制及孔隙水压力与变形之间的关系,采用物理模拟方法研究边坡变形失稳的全过程,分析孔隙水压力随降雨时间的变化规律及其与变形破坏的关系。研究结果表明：边坡后缘大方量堆载,改变了其应力条件,是滑坡产生的主要因素。场地施工改变了原有的地表水环境,连续强降雨致使大量下渗的雨水,不仅显著改变坡体应力条件,而且雨水沿着滑面运移软化滑带,是滑坡产生的重要诱发因素。孔隙水压力在坡体失稳过程中起着关键作用,填方体土碎屑、泥质含量大,下渗的雨水携带上部细小颗粒及滑带泥质成分至滑带附近,堵塞地下水消散通道,表现为坡体变形积累,孔隙水压力增加;边坡变形陡增,孔隙水压力降低。该滑坡破坏分为降雨下渗、滑带饱水软化、后缘产生裂缝、裂缝贯通-整体滑动4个阶段,为蠕滑-拉裂式滑坡。     

SH波在浅埋多个圆孔处的散射与地震动

研究了以任意方向入射的平面SH波在浅埋多个圆孔处的散射与地震动问题。利用SH散射的对称性和多极坐标方法构造了问题的位移解。当入射波的波长与圆孔的半径相比较小时,地震动将受到较大的影响。影响地震动有三个主要参数:(1)SH波的入射角α0;(2)入射波波数η,即圆形孔洞的半径与入射波半波长之比;(3)诸圆孔的埋置情况,诸孔的埋深hi/ai、孔心距Di/ai,即圆形孔洞至表面距离与圆半径之比和圆形孔洞中心的距离与半径之比。当η较大时,地震动幅值变化激烈,位移幅值可出现跳动和放大的现象。当诸圆孔的最小埋深量hi/ai和孔心距Di/ai超过10-12时,位移幅值恢复至半空间单一圆孔散射的情况,表明圆形孔洞的影响可被忽略。     

减载条件下高填方涵洞受力机制及基底压力

针对现有的理论方法主要关注涵顶土压力而未能考虑涵洞侧墙摩擦阻力对高填方涵洞结构受力状态的影响,提出了完整的减载条件下涵?土作用机制模型,推得涵洞侧墙摩擦力及基底压力的计算式。并将该理论方法的计算结果与数值模拟结果进行了比对,验证了该理论方法的正确性。研究结果表明,侧墙摩擦力沿墙身深度近似呈线性增加,并随填土高度的增加而增大;相同填土高度时,减载条件下的侧墙摩擦力大于非减载条件下侧墙摩擦力;采用减载措施虽然降低了涵顶垂直土压力,但是增大了涵测水平土压力,基底压力并未减小,现有的减载理论方法中不考虑侧墙摩擦力的影响是不合理的。     

某山区机场高填方滑坡变形特征分析

西南山区某机场高填方边坡在雨季结束后不久产生了变形。通过现场调查,坡体后部土面区出现了三条拉张裂缝,左右侧界也有明显变形迹象,坡脚五级马道水沟挤压变形严重,坡脚挡墙产生一小段垮塌变形。通过地表宏观变形判断坡体处于挤压变形阶段。对此段填方体滑坡及时实施了应急变形监测与工程地质勘察。通过地表变形监测曲线分析,由于错过了初始变形阶段的监测,该滑坡变形一开始就处于等速变形阶段。该滑坡在抗滑桩开挖过程中,变形明显加剧。坡体变形进入加速阶段后,变形速率及变形加速度较等速变形阶段成倍增加。在变形进入临界状态前,及时实施了坡体后部刷方减载,坡脚堆载反压的应急治理措施。应急治理措施实施后,坡体变形速率迅速减小,为永久治理工程的实施争取了时间。     

Surface-Layer Characteristics in the Stable Boundary Layer with Strong and Weak Winds

An extensive meteorological dataset obtained from the plumevalidation experiment conducted by the Electric Power Research Institute (EPRI) atKincaid during 1980–1981 is analysed for studying the characteristic differences in thesurface-layer parameters in strong and weak wind stable conditions. The surface-layerparameters are computed using the similarity functions _m and _h proposed byBeljaars and Holtslag. The weak winds are characterized using the geostrophic wind speedas well as the wind speed at the 10-m level. The surface fluxes are found to be finitein weak wind conditions.Empirical formulations for the eddy diffusivities of momentum(K_M) and heat (K_H), and drag (C_D) and heat exchange (C_H) coefficients, as powerlaw functions of the bulk Richardson number (Ri_B), are proposed under both strong andweak wind conditions. Results are close to those based on observations taken from the IndianInstitute of Technology low wind diffusion experiment, the Land surface processes experiment,the Hanford diffusion experiment, the Cabauw field experiment and the Cooperative Atmospheric SurfaceExchange Study 1999 (CASES-99) experiment. In addition, the fluxes obtained fromthe proposed empirical relations are in good agreement with those based on similarity theory as wellas the turbulence measurements taken from the CASES-99 experiment.     

西藏聂拉木地区纳兴组深切谷充填序列特征及意义

西藏聂拉木地区纳兴组深切谷充填序列特征及意义李祥辉，王成善（成都理工学院，成都６１００５９）关键词充填序列，深切谷，纳兴组，亚里，聂拉木研究区纳兴组下部深切谷体系发育于西藏南部珠穆朗玛峰与希夏邦马峰之间地区，剖面位置西距希夏邦马峰约３５ｋｍ，位于聂拉...     

注浆技术在城镇建设和整治中的应用

在城镇建设和整治中采用注浆技术，可以改良地层土的物理力学性能；在地层中造成固结体；可加固、顶升、纠偏因基础沉降而倾斜的建筑物；还可充填有大型裂隙和洞穴的地层或地下工程壁后空隙。以实例介绍了注浆技术及其在工程中发挥的作用。     

Induced seismicity in large-scale mining in the kola peninsula and monitoring to reveal informative precursors

Large volumes of rock mass, mined-out and moved within these deposits, resulted in irreversible changes in the geodynamic regime in the upper earth's crust of the adjacent territory. These changes manifest themselves in a more frequent occurrence of such intensive dynamic phenomena as tectonic rock bursts due to fault movement adjacent to the area which is mined-out and man-made earthquakes which sharply decrease mining safety and result in great material losses.To develop the prediction techniques of such phenomena, a monitoring system is created, based on the program of the Kola Complex of geodynamic measuring stations. Most of this system is realized in the region of the Khibiny apatite mines. The system provides regional seismological monitoring, local prediction of seismicity in separate areas of a rock mass and, determination of stress and strain in rock masses, local geophysical monitoring over the state of rocks in a rock mass as well as physical and mathematical modelling of geodynamic processes in the upper earth's crust.The investigations have resulted in the distinguishing of some regularities in manifestations of induced seismicity and tectonic rock bursts and in the determination of strain precursors of intensive seismic events in the Khibiny mines.The mechanism is provided by the induced seismicity which resulted from the anthropogenic impact on the geological medium. A geodynamic monitoring complex is described, which is used to reveal the precursors of powerful seismic eventsin situ, and monitoring results are shown, obtained in the Kola Complex of geodynamic stations. Methods of preventing tectonic rock bursts and induced earthquakes are presented.     

复合土钉墙技术在杂填土层基坑支护中的应用

结合复合土钉墙技术在杂填土层基坑中成功应用的工程实例，介绍了杂填土层基坑的特点、设计思想、施工过程中遇到的一些具体问题以及彩取的相应措施，为杂填土基坑支护摸索出一条崭新的道路。