Variation characteristics of temperature and moisture content of seasonal frozen soil during freezing process in Changchun,China

In China, seasonal frozen soil is widely distributed. The freezing damage of subgrade soil in Jilin Province has been one of major engineering geological problems troubling the safety of road, in which some common damage phenomena, such as frost heave, subsidence deformation and frost boiling, are all caused by water translocation. Aiming at the phenomenon, the changes of moisture content of seasonal frozen soil in Changchun City are mainly studied by long-term field observation and indoor testing of physical properties under different conditions, and then the variation characteristics of moisture content in soil under different compactness and temperature conditions are realized. The results show that the increasing section of moisture content and negative temperature section all lie in O. 0 - 1.0 m of subgrade. Both lowest air and earth temperature occur in January to February, and the most negative temperature ranges from -7℃ to -10℃.     

Application of ultrasonic CT method in nondestructive detection of interior defects in large scale concrete structural member of bridge

The ultrasonic computed tomography （USCT） method is derived from the basic principles of X-ray section scanning. This method records the arriving times of ultrasonic wave between the probes and the sources to ealculate the elastic wave velocity values in the section using the arrival times. Through analyzed the distribution Of elastic wave velocity in aim area, the information of the strength and the homogeneity of the investigated zone could be got indirectly. The authors introduced the operational principle of USCT and a practical case of using this method to detect the interior defects in large scale concrete structural member. Compared with other exploration methods, this method is more efficient and accurate.     

Application of TSD tunnel seismic prediction system in karst area

TSD is one of the classical methods of tunnel seismic prediction based on higher accuracy multi-wave multi-component seismology. The working principle of the TSD and an application example of the TSD on tunnel prediction in Chongqing are introduced in this paper. This system has two ports for speed signal and acceleration signal, and the equipment is more portable and easy to use. According to the application results we can conclude that the TSD prediction system is accurate and it has the wide application prospect in tunnel seismic detection.     

岩石质量描述图与岩石质量风险分析探讨

本文针对结构面间距最常见的两种分布形式－－负指数分布和对数正态分布，探讨了岩石质量指标（RQD）的Monte-Carlo模拟方法，首和无根据结构面间距分布密度函数产和一包含50万个随机结构面并按生成顺序排列的模拟真实岩体的总测线，然后为了和实际 钻探时以2米测线计算RQD相一致，在总测线上按均匀分布形式随机抽取大于等于2米的局部测线共5万个计算RQD单值，并进一步统计得出所有RQD的平均值，RQD累积分布曲及岩石质量描述图，对于自然界大部分岩体，可根据结构面间距统计参数，直接在本文得出的一系列岩石质量图上定出RQD平均值，岩石质量百分比（RQP）及岩石质量风险（RQR）。     

Dynamic Plastic Response of Circular Plates Resting on Fluid with Finite Deformation

This paper concerns the dynamic plastic response of a circular plate resting on fluid subjectedto a uniformly distributed rectangular load pulse with finite deformation.It is assumed that the fluid isincompressible and inviscous,and the plate is made of rigid-plastic material and simply supported along itsedge.By using the method of the Hankel integral transformation,the nonuniform fluid resistance is de-rived as the plate and the fluid is coupled.Finally,an analytic solution for a circular plate under a mediumload is obtained according to the equations of motion of the plate with finite deformation.     

Research on infiltration clogging effect and its application prospect in anti-seepage project

Clogging effect, as a new concept in geological engineering, is a phenomenon of permeability decreasing under seeping in reservoir dam foundation of the alluvial and diluvial deposits with deep and thick layer, coarse particle and high permeability in mountains-gully rivers of Tibetan Plateau. A clogging infiltration instrument has been designed successfully and a series of simulation tests have been done. Based on large amounts of data, it is confirmed that the existence of the clogging effect and the law of infiltration clogging is found out. Three indexes are proposed such as ＂optimal size of particle＂, ＂optimal size range of particle＂ and ＂characteristic pore＂, which are closely related with effect of infiltration clogging. The concept and results can offer a new idea to solve problems on anti-seepage of dam foundation in mountains-gully rivers environment and to study artificial clogging, meanwhile supplement of the concept of seepage deformation.     

西宁地区次生盐渍土的分布特征及地基处理方法

西宁地区次生盐渍土主要分布于山麓斜坡带高阶地和河谷高漫滩,前者属中～弱硫酸、亚硫酸盐渍土,且多具中等～强烈湿陷性,盐份主要来自斜坡后缘含盐碎屑岩风化物及易溶盐;后者为中等亚氯、亚硫酸盐渍土,溶于土中的盐份系浅层咸地下水常年毛细上升蒸发所致。其次生盐渍土的松胀性、溶陷性、腐蚀性较强,工程建设要引起重视。     

Probabilistic Analysis for Seismic Stability of Beach Earth Embankment

The current safety factor method for evaluating earth embankment stability is not very rational since the assessment of slope stability is really an uncertainty problem. In order to consider the random property of this problem, the probabilistic analysis is introduced herein. Finally, the stability of a real beach earth embankment is analysed by means of the suggested probabilitic approach. It may be seen that the results of analysis can represent the numerical assessment of the degree of seismic stability.     

An Improved Formulation for the Ultimate Static Strength of Tubular Joints subjected to Combined Loads

"The effect of interaction of loads on the ultimate static strength of tubular joints of offshore fixed platforms, is a practical problem. But there is still absence of rigorous theory to explain available experimental data and empirical criteria for the static strength of tubular joints. The idea of yield at hot spot of tubular joints is introduced in this paper. The interaction equations of plastic capacity for the tubular joints under combined loads (two and three different kinds) are derived. Thereafter the Yura's test data and empirical criteria of ultimate static strength for the tubular joints can be explained. The idea of classification of category of loads in accordance with experimental data and the present theory is suggested. Finally, the improved ultimate capacity equations for tubular joints are recommended. The physical significance of the coefficient of plastic reservation Qp is discussed.     

Optimum Design for Offshore Platform Structural Reliability

In this paper, the main problems concerning reliability design of offshore platform structure are described and the general steps for the use of Safety Coefficient Method are presented.