印尼苏门答腊8.7级大震对中国陆区的影响

发生在2004年12月26日的印尼苏门答腊8．7级地震，是全球有地震台网以来100多年中记录到的少数几次特大地震之一。初步汇集了在中国陆区观测到的地震活动、地壳形变、地下流体等多学科震时和震后效应的异常变化，包括地震活动性（特别是云南地区）的显著增强；地壳形变观测，尤其是钻孔应变观测记录到地壳应力-应变的震时和震后显著变化，以及地下水温度、化学成分、特别是水位的突出变化。同时，还从库仑破裂应力触发、动态应力触发以及下地壳和上地幔流动变形机制等方面，对这些大震效应作了一些成因机理讨论。     

岱海14 C测年的现代碳库效应研究*

碳库效应的复杂性是影响建立湖泊沉积物高精度年代序列的一大障碍。本项研究通过我国内蒙古半干旱区封闭湖泊表层沉积物、湖水、现生沉水植物狐尾藻、现生鲤鱼鱼骨和湖岸表层土壤等一系列样品的¹⁴ C年代测定,表明现代岱海确实存在碳库效应。碳库效应年龄因湖水盐度在湖区的不均而有所变化,岱海西部湖区弓坝河径流补给量大,湖水盐度较东部稍低,碳库效应年龄也略小于东部湖区。表层沉积物中有机质包含浮游生物和沉水植物的混合信息,因而其碳库效应年龄较沉水植物年龄轻,岱海湖心表层沉积物碳库效应年龄在2000a左右。这一碳库效应年龄较通过沉积钻孔¹⁴ C年龄线性回归获得的年龄偏大,可能的原因是在时间序列上碳库效应并非恒定。     

论"单位涌水量就是导水系数"

单位涌水量是井抽水水位降深换算为1 m时的单井出水量;导水系数是含水层宽度为1 m时,地下水水力坡度为1时的单宽流量.二者之间从定义上看毫无关系,但它们的单位(m3/d·m)(m2/d)是相同的.笔者经过多年探讨和初步试验后发现,单位涌水量就是管井抽水所利用含水层的导水系数.     

Reliability analysis of drilled shaft behavior using finite difference method and <Emphasis Type="Italic">Monte Carlo</Emphasis> simulation

Load displacement analysis of drilled shafts can be accomplished by utilizing the “t-z” method, which models soil resistance along the length and tip of the drilled shaft as a series of springs. For non-linear soil springs, the governing differential equation that describes the soil-structure interaction may be discretized into a set of algebraic equations based upon finite difference methods. This system of algebraic equations may be solved to determine the load–displacement behavior of the drilled shaft when subjected to compression or pullout. By combining the finite difference method with Monte Carlo simulation techniques, a probabilistic load–displacement analysis can be conducted. The probabilistic analysis is advantageous compared to standard factor of safety design because uncertainties with the shaft–soil interface and tip properties can be independently quantified. This paper presents a reliability analysis of drilled shaft behavior by combining the finite difference technique for analyzing non-linear load–displacement behavior with Monte Carlo simulation method. As a result we develop probabilistic relationships for drilled shaft design for both total stress (undrained) and effective stress (drained) parameters. The results are presented in the form of factor of safety or resistance factors suitable for serviceability design of drilled shafts.     

A Combined Three-Dimensional Geological-Geostatistical-Numerical Model of Underground Excavations in Rock

Summary. This paper exploits geological and borehole geotechnical data obtained in the exploratory phase of a tunneling project to investigate in a first place if the kriging interpolation scheme may effectively reproduce the spatial variability of rock mass quality (Rock Mass Rating, RMR) in the vicinity of tunnels. For this purpose a quick solver in Fortran has been developed that performs variography analysis of 3D spatial data, fast kriging estimations of RMR between borehole sampling locations at the centroids of the elements of the numerical model, and model validation. For the purpose of an integrated underground excavation design, a step further is made by incorporating into the 3D mechanical numerical model of the rock mass, the three-dimensional (3D) solid geological model, thus coupling the geology with the ground (geotechnical) model (i.e. each element of the numerical model is assigned a geological material). The mechanical properties of each finite difference cell (or Representative Elementary Volume) of the ground model were then prescribed according to its geological type, the spatial heterogeneity of the rock mass expressed quantitatively with the kriging model, and the upscaling calculations of the mechanical properties of the intact rocks determined in the laboratory, based on the size-effect (strength dependence on size) and Damage Theory. Furthermore, a preliminary numerical simulation of the advance of unsupported tunnels in the model of the heterogeneous rock mass was performed for illustration purposes.     

Structural and fabric analyses of basal slip zone of the Jin’nosuke-dani landslide, northern central Japan: its application to the slip mechanism of decollement

We describe in detail the deformation structures and textures of a large-scale landslide body that developed in the Betto-dani Valley in northern central Japan. We studied the shape-preferred orientation of clasts and clay flakes and the development of internal shear planes within the slip zone of the landslide. The slip has an average rate of 5–10 cm/year under the overburden pressure of approximately 1.6 MPa; these values are similar to those of the proto-decollement zone of the Nankai accretionary prism in SW Japan. The anisotropy of magnetic susceptibility of samples obtained from the slip zone reveals that the long axes of clay flakes define an imbricate structure. The slip was due to a long-term periodical creep, which occurs during the thaw seasons with an average slip rate of 0.16–0.32 μm/min. During the creep, the long axes of grains including clay flakes in the slip zone are developed from parallel to perpendicular to the slip direction. The observed textures provide a clue to elucidate the deformation textures and process in the decollement zone of the Nankai prism.     

Installation of a vertical slurry wall around an Italian quarry lake: complications arising and simulation of the effects on groundwater flow

Slurry walls are non-structural barriers that are constructed underground to impede groundwater flow or manage groundwater control problems. The study area is in the Piemonte plain (Italy), close to the River Po. Quarrying works carried out below the piezometric surface created two big quarry lakes. The local groundwater system is characterized by a lower semi-confined aquifer, which is overlain by a semi-permeable bed of clayey peat (aquitard) and an upper unconfined aquifer. Locally, the peat fades away and the granulometry of this horizon becomes silty sandy. A planned enlargement of the quarry will increase the size and depth of the quarry lakes. So the aquitard bed between the two aquifers will be damaged, creating a mixing rate of groundwater. Such a procedure would not be compatible with the presence of two municipal wells upstream from the quarries. Consequently, the installation of a vertical diaphragm (slurry wall) is recommended to separate the aquifers and to act as a filter for the groundwater flowing from the unconfined to the semi-confined aquifer. To predict the consequences caused by the installation of the vertical diaphragm separating the unconfined aquifer and the semi-confined one, a specifically adjusted finite-difference model was used. The model showed a maximum rising of the water table equal to 12 cm, just upstream of the diaphragm and for a distance of about 100 m, and a maximum lowering of 2 cm just downstream of the diaphragm. However, the slurry wall would not cause any change in the piezometric head in the area where there are municipal wells and, hence, will not have any negative effect on the functionality of the municipal wells. Moreover, the migration of water from the unconfined aquifer through the vertical diaphragm will stimulate a series of attenuation and auto-depuration processes of eventual contaminants. These processes are due to the higher crossing time that the groundwater flow takes to go through the vertical barrier (t _a = 96.5 days, whereas for the horizontal semi-permeable layer t _a = 9.6 days). So, the vertical diaphragm can be a resolutive element, representing a mediation and separation factor between the unconfined and the semi-confined aquifers along the border of the quarrying areas, and a protective barrier for the water quality of the quarry lake and the semi-confined aquifer.     

Influence of initial density of cohesionless soil on evolution of passive earth pressure

This paper focuses on the influence of the initial void ratio on the evolution of the passive earth pressure and the formation of shear zones in a dry sand body behind a retaining wall. For the numerical simulation a rigid and very rough retaining wall undergoing a horizontal translation against the backfill is considered. The essential mechanical properties of cohesionless granular soil are described with a micro-polar hypoplastic model which takes into account stresses and couple stresses, pressure dependent limit void ratios and the mean grain size as a characteristic length. Numerical investigations are carried out with an initially medium dense and initially loose sand using a homogeneous and random distribution of the initial void ratio. The geometry of calculated shear zones is discussed and compared with a corresponding laboratory model test.     

从盘县红岩洞金矿的发现看化探找矿方法及效果

盘县红岩洞金矿是应用地球化学勘查方法发现的金矿体,回顾发现该矿体的过程,研究地球化学特征,讨论应用地球化学勘查方法寻找微细浸染型金矿的工作方法及经验。     

腐解9个月后杉木枯枝落叶化感物质对杉木的化感作用

采用有机溶剂与蒸馏水混和浸提杉木枯枝落叶腐解9个月后化感物质,应用杉木种子发芽试验进行生物检测.结果表明:杉木枯枝落叶腐解9个月后,杉木枯枝落叶中的弱极性化感物质对绝对发芽率、绝对发芽势、胚根长、胚轴长及干物质量等指标表现为抑制作用,对鲜物质量则表现为轻微的促进作用;极性化感物质对杉木种子发芽各指标均等表现为抑制作用.腐解土中的弱极性化感物质对杉木种子发芽各指标均表现为抑制作用,极性化感物质对绝对发芽率、绝对发芽势、胚轴长及干物质量等表现为抑制作用,但对胚根长、鲜物质量表现为促进作用.