钻孔引发基坑管涌事故的分析与处理对策

地下室开挖与基础施工过程中,当坑底存在承压水,如设计考虑不周或施工方法不当,因钻孔穿透承压含水层等原因,将导致管涌发生。结合浙江宁波某基坑管涌处理工程实例,提出采用钢套管、高压旋喷桩、双液注浆的综合处理技术,实践证明,提出的技术可以有效处理类似事故。     

印度地理信息产业发展基础与现状研究

主要从地理信息资源生产管理体制、空间基础设施建设、产业政策3个方面分析了印度地理信息产业发展基础,并对当前印度地理信息产业规模、市场、企业、人才培养以及发展潜力等方面的现状进行了研究,对比我国分析了当前印度地理信息产业发展的优势和存在的制约。     

MODULATION OF MADDEN-JULIAN OSCILLATION ON TIBETAN PLATEAU VORTEX

This study uses NCEP/NCAR daily reanalysis data, NOAA outgoing long-wave radiation (OLR) data, the real-time multivariate MJO (RMM) index from the Australian Bureau of Meteorology and Tibetan Plateau vortex (TPV) data from the Chengdu Institute of Plateau Meteorology to discuss modulation of the Madden-Julian Oscillation (MJO) on the Tibetan Plateau Vortex (TPV). Wavelet and composite analysis are used. Results show that the MJO plays an important role in the occurrence of the TPV that the number of TPVs generated within an active period of the MJO is three times as much as that during an inactive period. In addition, during the active period, the number of the TPVs generated in phases 1 and 2 is larger than that in phases 3 and 7. After compositing phases 1 and 7 separately, all meteorological elements in phase 1 are apparently conducive to the generation of the TPV, whereas those in phase 7 are somewhat constrained. With its eastward propagation process, the MJO convection centre spreads eastward, and the vertical circulation within the tropical atmosphere changes. Due to the interaction between the mid-latitude and low-latitude atmosphere, changes occur in the baroclinic characteristics of the atmosphere, the available potential energy and eddy available potential energy of the atmosphere, and the circulation structures of the atmosphere over the Tibetan Plateau (TP) and surrounding areas. This results in significantly different water vapour transportation and latent heat distribution. Advantageous and disadvantageous conditions therefore alternate, leading to a significant difference among the numbers of plateau vortex in different phases.     

基于卡尔曼滤波的离散灰度模型在基坑沉降数据的研究

为了提高深基坑开挖过程中实时沉降监测预测的可靠性与准确性,保障基坑施工和周边环境安全,针对深基坑开挖过程中周围底层移动、施工、环境因素及实际观测过程中原始数据存在较多噪声对原始沉降数据产生一定影响等诸多问题。本文考虑使用卡尔曼滤波理论对沉降数据进行去噪预处理,并建立离散灰度模型,通过该模型对沉降数据进行分析及预测。通过实验数据分析处理,验证模型预测精度有了一定的提高,且具有一定的参考价值。     

Deep Penetration of Spudcan Foundation into Double Layered Soils

The spudcan foundation has been widely used in offshore engineering for jack-up figs. However, “punch through”failure often occurs where a stronger soil layer overlays a softer soil layer. In this study, spudcan penetration into double layered soils is investigated numerically. The soil profde is set up as a stronger soil layer overlaying a softer soil layer,with the soil strength ratio ( bottom soil strength / top soil strength) varied from 0.1 to 1.0 ( 1 means uniform soil). The bearing bohaviour is discussed and the beating capacity factors are given for various cases involving different layer thicknesses and different strength ratios of the two clay layers. The development of the plastic zones and the effect of soil selfweight on the beating capacity are also discussed. From this study, it is found that, when a spudcan is distant from the soil layer boundary, the spudean can be analysed with single soil layer data. However, when a spudcan becomes closer to the soil boundary layer, the influence of the lower soft soil layer is significant, and the beating capacity of the spudean decreases. The critical distance is an indication of the occurrence of “punch through” failure. The critical distance between the spudcan and the layer boundary is larger for a rough spudean than the one for a smooth one, and the critical distance decreases with increasing soil strength ratio. The depth of cavity formed during initial spudcan penetration depends on the top layer soil strength, soil strength ratio and unit soil self-weight, and the cavity affects the spudcan beating behaviour as well.     

Underwater Explosion Treatment of Marine Soft Foundation

The consolidation of soft foundation is a problem that commonly appears in harbor construction engineering on muddy coast. Introduced in this paper is the experimental study on underwater explosion treatment of soft foundation, including the regulations of explosion hollow development and medium movement, the law of similarity of densification and settlement of filled stone mass by shock wave pressure and explosion energy and their construction technologies, etc. A number of projects have been completed by applying this new technique, and the technique itself has been proved practicable.     

A Study on Impervious and Heat-Insulating Performance of Geomembrane Composites Within Breakwater

This paper investigates the performance of geomembrane composites used as impervious andheat-insulating lining within a breakwater for a power station.The seepage field,distribution ofstress-strain contour and seepage discharge of hot water which has been treated as the inner thermalsource in the calculation of heat-insulation,have been given by three-dimensional calculation method coup-ling seepage with stress.The results indicate that the impervious and heat-insulation effect ofgeomembrane composites is significant.     

Finite Element Analysis of soft Foundation Strengthening by Vacuum Loading from Lower Position

Strengthening soft foundation by vacuum loading from lower position is a new method of ac-celerating the consolidation of dredger fill.This paper presents the mechanism of soft foundation strength-ening by vacuum loading from lower position and evaluates the effectiveness of this method under variousboundary conditions by means of finite element method(FEM)on the basis of Biot's consolidationtheory.     

日照港十六号路软基处理工程

介绍了日照港十六号路软基加固方案及其加固效果