闽江河口区湿地生态旅游环境容量研究

本文讨论了生态旅游环境容量的定义及内涵，分析了生态旅游环境容量的特征及构成，在此基础上估算了闽江河口区湿地生态旅游环境容量．结果表明：闽江河口区湿地生态旅游环境容量的限制因子是鳝鱼滩自然保护区生态旅游环境空间容量．鳝鱼滩旅游步行道可分成南路和北路，北路为水路游线，南路为陆路游线．北路游线环境空间日容量为800人次／d，南路游线环境空间日容量为1144人次／d．鳝鱼滩湿地生态旅游环境空间年容量为451202人次／a．这一环境容量可作为闽江河口区湿地生态旅游活动环境容量的最高限制量．     

全新世以来江苏中部地区海岸的淤进

全新世以来，江苏中部地区经历了由海洋向陆地的演化过程，海岸线的演化以淤进为主，大致经历了三个过程：早全新世（10～7kaBP）本区为浅海环境，海岸线抵西部山地,中全新世（7～3kaBP）海岸以缓慢淤进为主，古砂堤发育．晚全新世（3kaBP以来）因黄河夺淮，海岸东迁迅速，形成广袤的滨海平原．     

Vulnerability Assessment at Village Level Due to Tides,Surges and Wave Setup

An assessment of cyclone risk and vulnerability at the village level has evolved, which is an important component of the information system for local level development action plans for preparedness and mitigation. Here, a case study for the Nellore district along the east coast of India is considered. Using maximum probable surges along the coast, total water level (TWL) due to the combined effect of surge, tide, and wind wave is computed for the most vulnerable coastal villages of the Nellore district due to any tropical cyclones. The computations suggest that the TWL along the Nellore coast varies from 2 m in the south to 4 m in the north.     

Estimation of Land Subsidence Based on Groundwater Flow Model

This article presents an approach for estimating land subsidence due to withdrawal of groundwater. The proposed method calculates the groundwater seepage in 3-D-condition and calculates the land subsidence one-dimensionally. The governing equation on groundwater seepage is based on the three-dimensional mass conservation law and the principle of effective stress. The land subsidence calculation method is derived based on the following assumptions: (1) displacements occur only in the vertical direction, and (2) in vertical direction the total stresses do not change. The governing equation is solved by numerical method, i.e., finite element method (FEM) in spatial discretization and finite difference method (FDM) in time series discretization. In FEM Galerkin method is adopted and in FDM, lumped matrix method is employed. The proposed method is calibrated via analyzing 1-D consolidation problem and the results are compared with those from Terzaghi's one-dimensional consolidation theory and oedometer test. The proposed method is employed to analyze the consolidation of a soft layer due to withdrawal of groundwater from an aquifer under it. Moreover, this method is also applied to a field case of land subsidence due to groundwater pumping in a gas production field in Japan. The analytical results are compared with the field observed data. The results show that this approach simulates the field case well.     

Geotechnical characterization of slump scars,eroded slopes,and correlated deposits on continental margins: Gulf of Lions,Western Mediterranean sea

Abstract

Vertical variations of geotechnical properties in the uppermost sediment layers characterize the main sedimentary processes acting on the construction and destruction of progressive‐type continental slopes. In the Gulf of Lions, the original thicknesses and distribution of the uppermost sedimentary layers of the continental slope and rise, which consist of Holocene muds overlying Pleistocene muds, have been greatly modified by erosion and several kinds of slope failure processes. Each process is typified through sets of geotechnical properties measured in the eroded or slumped sections and in the associated sediment accumulations.

In slump scars, the water‐rich Holocene muds lie on fine, overconsolidated, Pleistocene muds with high plasticity and low shear strength. In bottom current‐eroded slopes, where modern sedimentation is extremely reduced, the Pleistocene muds frequently outcrop and may sometimes be overlain by a very thin layer of Holocene muds. The Pleistocene muds of eroded slopes are overconsolidated and more silty and less plastic than the Pleistocene muds from slopes affected by slope failure, their shear strength being 10 times greater.

Deposits at the toe of slumps are very often formed by several superposed three‐layer units (triplets of interstratified Holocene, transitional, and Pleistocene layers) issued from retrogressive slumping occurring in the slump scars above their head area. The main body of each layer is then relatively undisturbed, showing the usual burial geotechnical gradients due to overburden pressure (i.e., decrease of water content and increase of unit weight and shear strength). At the toe of bottom current‐eroded slopes, a thick and homogeneous layer of Holocene muds overlies the Pleistocene muds; this Holocene layer has unappreciable burial depth gradient of its geotechnical parameters because of a high rate of modem and continuous deposition.     

Field Study on the Behavior of Destructive and Non-Destructive Piles Under Compression

This paper presents a series of full-scale load tests on long bored piles instrumented with strain gauges along the shafts, including eight field tests of piles loaded to failure and one non-destructive pile load test. The load-displacement response, skin friction, end resistance, and the threshold of the pile-soil relative displacement for fully mobilizing skin resistance were discussed. A simple softening model was proposed to describe the degradation behavior of the skin friction along the pile-soil interface and the load-displacement relationship developed at the pile base. It is found that the shaft resistance degradation investigated in the non-destructive load test only occurs at a shallow depth, and the skin friction of deeper soil is not fully developed. However, unlike the results of the non-destructive load tests, the softening is accompanied by a reduction in skin friction and observed to be along the whole pile depth. The thresholds of pile-soil relative displacement for fully mobilizing skin resistances in different soils have been found to be in the range 0.6% to 2.4% of the pile diameter. Moreover, in practical applications, a bilinear model is assumed to be feasible in analyzing the load-settlement relationship developed at the end of non-destructive pile, whereas the load transmission curve of the soils below the pile base corresponds to a softening model in the field tests of piles loaded to failure.     

春末海南万宁海域浮游动物群落结构研究

根据 2012 年春末在海南万宁海域所采集的浮游动物样品, 对该海域浮游动物的种类组成、饵料生物量、丰度和生物多样性进行了探讨, 采用大型多元统计软件 PRIMER5.0 对浮游动物的群落结构进行了分析。结果表明调查海域共有浮游动物 70 种、浮游幼虫 10 个类群, 其中优势种共有 6 种: 双尾溞 纽鳃樽、多毛类幼虫、短角长腹剑水蚤、鸟喙尖头 、尖额真猛水蚤和小拟哲水蚤。浮游动物生物量和丰度的平面分布相似, 主要分布在调查海域的北部和中部近岸处。 浮游动物具有较高的均匀度(0.70), 生物多样性指数较高(3.10)。群落结构聚类分析显示浮游动物可以分为 5 个生态类群。     

编织袋充填砂结构在围堰工程中的应用

结合青岛市四方区围海造地工程的实例,分析了在厚度较大的软弱地基层上水下铺设大型编织布袋作为围堰的主体结构的优点和结构特点,重点介绍了施工工艺以及在施工过程中需注意的问题。     

一种优化模糊度搜索方法的研究

对于高精度测量和导航,GPS载波相位整周模糊度的快速求解仍然是一个难点,尤其对于单频接收机。提出一种快速求解整周模糊度的方法,其基本思想采用分步求解,首先应用最小二乘模糊去耦调节法(LAMBDA)搜索出来的模糊度作为初始值,然后应用卫星分组方法降低搜索维数,并应用极大似然准则,构造搜索函数,最后应用最优化原理,搜索出最优的模糊度参数,并从三个方面对其进行检验,即RATIO检验,OVT检验,多项式拟合残差检验。为验证该算法,我们用单频GPS接收机进行了实验,利用本文方法在11 S以内正确确定了模糊度,其基线长误差小于3MM,表明该方法不但可以改进模糊度的搜索速度,而且可以进一步提高其可靠性和成功率。该方法可广泛应用于定向及姿态测量。     

GPS变形监测动态数据处理中卡尔曼滤波的应用

介绍了卡尔曼滤波的基本原理,针对常规GPS变形监测数据处理中存在着不连续、非实时的缺点,结合卡尔曼滤波的特点,运用三峡实测数据对GPS变形监测动态数据处理中卡尔曼滤波的应用进行研究。并采用各点点位位移速度图对所建立的函数模型进行验证,同时对状态方程的建立及初始值的选取进行分析总结。