喀斯特地区某桩基工程溶洞的处理措施

本文总结了粤北喀斯特地区某桩基础工程的施工过程,论述了喀斯特地区的溶洞特征及所采取的处理措施。     

浅议高压喷射注浆技术

高压喷射注浆技术是近年发展起来的一种基础处理新技术,它是利用高压载能介质将软弱土体冲切破碎后注入固结浆液在原位混合凝固,达到强化地基的目的。该技术多用于深层软土地基加固,建造堤坝防渗帷幕及高强度的防渗挡土墙等。本文就这项新技术及其机具设备与安装、施工程序、应用前景作了概括介绍。     

THE EROSIONAL PROCESS OF THE SOFT SHORE OF CHINA IN THE RECENT DECADES

ＴＨＥ ＥＲＯＳＩＯＮＡＬ ＰＲＯＣＥＳＳ ＯＦ ＴＨＥ ＳＯＦＴ ＳＨＯＲＥ ＯＦ ＣＨＩＮＡ ＩＮ ＴＨＥ ＲＥＣＥＮＴ ＤＥＣＡＤＥＳ ＷａｎｇＷｅｎｈａｉ（王文海）；ＷｕＳａｎｇｙｕｎ（吴桑云）；ＸｉａＤｏｎｇｘｉｎｇ（夏东兴）（ＦｉｒｓｔＩ...     

Simple formulas for the dynamic stiffness of pile groups

Simple formulas are derived for the dynamic stiffness of pile group foundations subjected to horizontal and rocking dynamic loads. The formulations are based on the construction of a general model of impedance matrices as the condensation of matrices of mass, damping, and stiffness, and on the identification of the values of these matrices on an extensive database of numerical experiments computed using coupled finite element–boundary element models. The formulations obtained can be readily used for the design of both floating piles on homogeneous half‐space and end‐bearing piles and are applicable for a wide range of mechanical and geometrical parameters of the soil and piles, in particular for large pile groups. For the seismic design of a building, the use of the simple formulas rather than a full computational model is shown to induce little error on the evaluation of the response spectra and time histories. Copyright © 2009 John Wiley & Sons, Ltd.     

Theoretical Model and Dynamic Analysis of Soft Yoke Mooring System

As a popular solution for mooring an FPSO （Floating Production, Storage and Offloading） permanently in shallow water, the soft yoke mooring system has been widely used in ocean oil production activities in the Bohai Bay of China. In order to simulate the interaction mechanism and conduct dynamic analysis of the soft yoke mooring system, a theoretical model with basic dynamic equations is established. A numerical iteration algorithm based on error estimation is developed to solve the equations and calculate the dynanfic response of the mooring system due to FPSO motions. Validation is conducted by wave basin experimentation. It is shown that the numerical simulation takes only a few iteration times and the final errors are small. Furthermore, the calculated results of both the static and dynamic responses agree well with those ones obtained by the model test. It indicates that the efficiency, the precision, the reliability and the validity of the developed numerical algorithm and program are rather good. It is proposed to develop a real-time monitoring system to further monitor the dynamic performance of the FPSO with a soft yoke mooring system under various real sea environments.     

Experimental study on pore water pressure dissipation of mucky soil

Pore water pressure has an important influence on mechanical properties of soil. The authors studied the characteristics of pore water pressure dissipating of mucky soil under consolidated-drained condition by using refitted triaxial instrument and analyzed the variation of pore pressure coefficient with consolidation pressure. The results show that the dissipating of pore water pressure behaves in different ways depends on different styles of loading. What is more, the pore water pressure coefficient of mucky soil is less than 1. As the compactness of soil increases and moisture content reduces, the value of B reduces. There is a staggered dissipating in the process of consolidation, in which it is a mutate point when U/P is 80%. It is helpful to establish the pore water pressure model and study the strength-deformation of soil in process of consolidation.     

Landscape Effects of Land Consolidation Projects in Central China——A Case Study of Tianmen City,Hubei Province

The goal of land consolidation in China is still to develop agricultural production. The study of landscape effects of land consolidation projects （LCPs） faces many difficulties because of the lack of government＇s interest and data. This paper, taking Tianmen City of Hubei Province in Central China as an example, presents a methodology for analyzing landscape effects of LCPs by GIS and Fragstats3.3. It describes landscape effects with indexes of Patch Density （PD）, Largest Patch Index （LPI）, Landscape Shape Index （LSI）, Interspersion and Juxtaposition Index （IJI）, Aggregation Index （AI）, and Shannon＇s Diversity Index （SHDI）, showing more regular shape, simpler structure and less habitat diversity after LCPs. It computes ten landscape indexes of four categories of patches including Cultivated Land, Road, Water Channel, and River and Pond. The indexes show that 1） cultivated land becomes more fragmental in patch area, less irregular in patch shape and more concentrated in block; 2） the transport capacity of roads and irrigation and drainage capacity of water channels have been improved; 3） the landscape change of river and pond can be summarized as decreasing scale, more regular shape, reducing connectivity and diversity of the class. LCPs can facilitate agricultural production as well as protect cultivated land and food security. However, it is doubted that the increase of cultivated land from LCPs results from the reducing in landscape diversity of water area.     

我国土地整理存在的问题及建议

根据编写审查土地整理规划设计、预算,竣工验收等一系列工作经验,通过分析目前我国土地整理工作出现的规划设计与实际脱节、施工管理不到位、资金不足、缺乏后期管护等诸多问题,提出了相应的对策建议,以期推动土地整理事业的健康发展。     

深井降水设计与施工若干问题探讨

探讨深井降水布井原则、设计参数的选择与计算等问题;分析深井降水对周围环境的影响并提出防范措施;总结深井降水施工方面的经验。     

二次灌浆在电解槽沉降基础加固复位中的应用

广西某电解铝车间电解槽沉降基础在采用直孔帷幕灌浆加固的基础上,利用斜孔在有限空间进行二次灌浆加固复位,通过合理控制灌浆压力和灌浆量或间歇灌浆等措施,实行测量跟踪观测控制每次灌浆的抬升量,成功地将电解槽沉降基础抬升复位。