土地整理中基于TIN结构的土方计算     

潘凤阁 《测绘与空间地理信息》2008,31(2):160-164

分析了TIN在土地整理中的地面整平(切割面水平或有一定坡度)、河道(或水渠)开挖及筑堤中的土方量计算和水域容积中体积计算等方面的应用。阐述了利用TIN进行体积计算的原理,结合地面整平与河道开挖介绍了应用方法。  相似文献   

Assessment of Marine Clay Improvement Under Reclamation Fills by in-situ Testing Methods     

A. Arulrajah  H. Nikraz  M. W. Bo 《Geotechnical and Geological Engineering》2006,24(2):219-226

In ground improvement projects with prefabricated vertical drains, the duration of the preloading period is set in advance based on the predetermined time rate of consolidation of the compressible layer. If prediction is accurately done, the required degree of consolidation is met at the pre-determined preloading time. As such, there is a requirement for in-situ tests to be carried out just prior to the removal of surcharge to assess the degree of consolidation of the improved ground. In-situ tests were carried out after 23 months of surcharge loading at the In-Situ Test Site within the Changi East Reclamation Project in the Republic of Singapore. In-situ testing works in this research study comprises the use of field vane shear, piezocone, flat dilatometer and self-boring pressuremeter. The in-situ tests were carried out to determine the shear strength and degree of consolidation of the Singapore marine clay at Changi after 23 months of surcharge loading. The In-Situ Test Site consisted of a Vertical Drain Area as well as an untreated Control Area. Both areas were located adjacent to each other and were surcharged simultaneously to the same level and surcharge left in place for a period of 23 months. Comparison was made between the in-situ test results of the Vertical Drain Area and the untreated Control Area.  相似文献   

VTI介质多波速度与各向异性系数求取及应用   总被引：1，自引：0，他引：1  

罗省贤  李录明  陈春继 《物探化探计算技术》2005,27(3):214-218

针对具有垂直对称轴的横向各向同性(VTI)介质,研究了多波速度与地层各向异性系数之间的关系。采用适应大偏移距以及强各向异性介质的双平方根方程,进行速度和各向异性系数分析,并将批量计算与交互解释相结合,实现了高精度各向异性介质多波速度与各向异性系数提取,并形成了一套利用多波地震资料求取地震波纵、横波速度及各向异性系数的方法和软件。所求取的参数可用于多波地震资料处理,提高多波资料的成像质量,也可为地层地质解释提供参考。实际资料的应用效果证明了该方法和软件的正确性及有效性。  相似文献   

EFG法在土体固结中的应用   总被引：4，自引：0，他引：4  

张延军  唐红兵 《吉林大学学报(地球科学版)》2002,32(1):77-80

EFGM作为一种新的数值计算方法，具有只需节点信息而无段单元的特性，故在解固结方程方面有很大的优势。在计算分析中，此法容易构造固结方程的EFGM刚度矩阵和处理不同边界条件。对单面排水等条件的计算结果表明，EFGM在解决固结变形问题上，精度较高，处理边界准确。  相似文献   

自重固结与土层的固结状态初探     

赵卫楚 《华东地质学院学报》2003,26(3):267-270

介绍了沉积厚度与时问平方根和沉积厚度与时间呈直线关系、底面不排水时沉积过程中固结的Gibson理论解答以及不考虑沉积时固结作用、底面不排水时沉积后自重固结的Terzaphi理论解答，据此分析了上述两种沉积模式不同沉积速率时目前仍处于沉积过程的土层的固结状态，求算出了停止沉积后土层固结所需的最长时问，指出业已停止沉积数百年以上的土层一般不应处于欠固结状态。  相似文献   

真空-堆载预压处理高速公路软基的有限元计算   总被引：10，自引：1，他引：10  

刘汉龙  彭劼  陈永辉  郑绍君 《岩土力学》2003,24(6):1029-1033

根据高速公路路基的变形特点，提出了真空-堆载联合预压法处理软基的三维Biot固结有限元计算模型，将砂井按照实际尺寸划分单元，避免了平面计算方法中的砂井处理的问题，较以往的平面数值方法更接近实际情况。结合修正剑桥模型，对某真空-堆载联合预压试验段进行了计算、分析，结果令人满意。  相似文献   

比奥固结理论在堆载预压加固工程场地中运用   总被引：4，自引：2，他引：4  

徐书平  刘祖德 《岩土力学》2003,24(2):307-310

运用平面应变比奥固结有限单元法，对南京某钢铁厂江边原料厂采用堆载预压结合塑料排水板处理的软土地基进行了计算，得到了较为理想的效果。计算中将塑料排水板合理地简化成等效砂墙，理论计算结果与实测结果吻合较好。验证了计算方法是合理可行的。  相似文献   

软土大变形固结计算中参数识别的遗传算法     

吴振君  施斌  亓军强 《水文地质工程地质》2003,30(4):35-38

含水量很高的饱和软土在外荷载作用下沉降很大,小变形分析误差太大,必须通过大变形非线性固结计算来模拟。遗传算法是一种全局优化和搜索的仿生算法。近年来随着工程领域中复杂的大规模非线性系统的出现,遗传算法日益得到青睐,目前已经广泛应用到各个领域中。本文对遗传算法做了改进,主要体现在杂交算子的选取和轮盘赌模型的模拟退火拉伸,并将其用于饱和软土的大变形固结分析,解决其中的关键参数识别问题。研究表明该方法是行之有效的,值得进一步研究探索。  相似文献   

Scattering of elastic waves by a general anisotropic basin. Part 2: a 3D model     

Marijan Dravinski 《地震工程与结构动力学》2003,32(5):653-670

Scattering of plane harmonic waves by a three‐dimensional basin of arbitrary shape embedded within elastic half‐space is investigated by using an indirect boundary integral equation approach. The materials of the basin and the half‐space are assumed to be the most general anisotropic, homogeneous, linearly elastic solids without any material symmetry (i.e. triclinic). The unknown scattered waves are expressed in terms of three‐dimensional triclinic time harmonic full‐space Green's functions. The results have been tested by comparing the surface response of semi spherical isotropic and transversely isotropic basins for which the numerical solutions are available. Surface displacements are presented for a semicircular basin subjected to a vertical incident plane harmonic pseudo‐P‐, SV‐, or SH‐wave. These results are compared with the motion obtained for the corresponding equivalent isotropic models. The results show that presence of the basin may cause significant amplification of ground motion when compared to the free‐field displacements. The peak amplitude of the predominant component of surface motion is smaller for the anisotropic basin than for the corresponding isotropic one. Anisotropic response may be asymmetric even for symmetric geometry and incidence. Anisotropic surface displacement generally includes all three components of motion which may not be the case for the isotropic results. Furthermore, anisotropic response strongly depends upon the nature of the incident wave, degree of material anisotropy and the azimuthal orientation of the observation station. These results clearly demonstrate the importance of anisotropy in amplification of surface ground motion. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Land subsidence caused by groundwater exploitation in Suzhou City,China   总被引：10，自引：2，他引：10  

Chongxi Chen  Shunping Pei  Jiu Jiao 《Hydrogeology Journal》2003,11(2):275-287

Suzhou City, located at the lower reaches of the Yangtze River in southeastern Jiangsu Province, is one of the few cities in China which suffer from severe ground settlement. A research project was carried out to investigate this problem. Geological and hydrogeological studies show that there is a multi-layered aquifer system with three distinct, soft mud layers of marine and lagoonal origins. An examination of historical records of groundwater extraction, water levels, and ground settlement shows that the ground subsidence is associated with the continuously increasing groundwater extraction in the deep, confined aquifer. It is believed that the consolidation of the soft mud layers, especially the third layer which is thick and close to the main pumped aquifer, contributes to the ground settlement. A three-dimensional finite difference numerical model representing the multi-layered aquifer system was developed to study the ground settlement in response to groundwater extraction. By calibrating the model with both the measured groundwater level and ground settlement, the aquifer parameters were estimated. The model outputs fit reasonably well with the observed results, which indicates that the numerical model can reproduce the dynamic processes of both groundwater flow and soil consolidation. The hydraulic conductivity of the third mud layer near the center of the ground settlement has been reduced by over 30% in the last 14 years. The gradual deterioration in the hydraulic conductivity of the mud may have significant adverse effect on the sustainable groundwater resource of the deep confined aquifer, since the recharge from the shallow aquifers through the mud layer is the only source of water to the deep aquifer. An analysis of the spatial distributions of groundwater drawdown and ground settlement shows that the area with maximum drawdown is not necessarily the area with maximum ground settlement due to the occurrence of the soft mud layer. A simple reallocation in pumping rates on the basis of the spatial distribution of the thick mud layer could significantly reduce the ground settlement. Electronic Publication  相似文献