Concept of system reliability is introduced.Utilizing narrow limit range method system reliability analysis of composite foundation of cement injection pile is analyzed.Practice show this method is satisfied to meet engineering requirements,which provide good references for engineering design of composite foundation of cement injection pile.

Based on grey system theory,GM(1,1) mode of unequal step length of the ultimate bearing capacity and pile block settlement of foundation piles was established according to measured date of eight foundation piles' static load test.The imitation of Q-S curve was realized.The predictor value of the ultimate bearing capacity and pile block settlement of foundation a pile were analyzed by the limited measurement data and was modified by grey system theory.The results indicate that this method has great practical application value.

Through Choosing the testing samples of silty soil from five projects in Handan downtown,the tests are carried for the dynamic shear modulus G_d and the damping ratio λ of unsaturated silty soil by using dynamic triaxial apparatus with the DDS-70 computer controlled electromagnetic type.The effects of the confining pressure,the level of shear strain,porous ratio and clay particle content to the modulus and the ratio are discussed and the results from the tests are analyzed by using Hardin-Drnevich model.The formula for the dynamic shear modulus of the silty soil in Handan downtown areas is given,which provides the basis for the foundation design.

膨胀土是一种多裂隙并具有显著胀缩性的粘性土,它常常给工程建设造成破坏。利用人工改性的方法能够在一定程度上克服其对湿、热的敏感性。对膨胀土地基改性处理方法进行了总结和评述,目前膨胀土的改性方法可以分为物理改性法、化学改性法和生物改性法三种。物理改性法施工简单,但施工条件、适用范围有限;化学改性法从理论上讲可以根本解决膨胀土的胀缩性,是目前应用最多的改性方法,但施工情况复杂、工程费用比较高、对环境造成污染、对操作人员身体健康也有伤害等;生物改性法适用范围比较小,一般和别的方法结合使用。在系统总结前人工作的基础上展望了膨胀土地基改性处理的研究方向和发展趋势。

考虑了临界桩长对沉降计算的影响,引入3层模量法并结合具体工程实例对水泥土深层搅拌桩沉降进行了分析,得出用三层模量法计算深层搅拌复合地基的沉降更具准确性。

According to random field theory,this paper gets the formula to confirm statistic characteristics of cement spraying's bearing capacity by using static cone penetration resistance force,calculates the reliable index of cement spraying's bearing capacity combined with practical engineering,analyzes the factors influenced the index,and finally gets the reliable index.

将相同含水量、相同干密度的邯郸地区膨胀土,在不同的尿素含量、不同龄期和不同竖向压力作用下进行变形试验。研究结果表明,改性处理后膨胀土的膨胀力、膨胀率和自由膨胀率分别由原来的111.16kPa、6.02%、72%下降为19.81kPa、0.01%、7.9%。尿素对膨胀土的膨胀性有很好的抑制作用。

For this kind of composite ground,some basic regularity of deformation,strength,load transferring along depth,interaction between pile and soil,deformation characters,and so on,have been obtained;Debating the influence of module radio、pile lengthl、oad and pile top stress,getting some worthy conclusion in engineering.

The relationships between strengthening effect of lateral friction and intensity of the DJM pile body,length of pile,modulus of compressibility of the pile-tip soil and the changing load on top of the pile were analyzed based on the data of static load test of deep jetting mixing(DJM) pile at one building site in Handan City by using finite element method according to Meyerhof theory.The results show that the modulus of compressibility of the pile-tip soil has more bigger influence on strengthening effect at(4～6)B of the bottom of pile.The conclusions have guidance for design of DJM pile composite foundation.

论文根据复合地基理论,结合某高速公路碎石桩加固互层路基的工程实践,分析了影响承载力的主要因素,探讨了砂土和粘性土互层地基的设计方法以及在检测中应注意的问题,得到了一些具有一定工程意义的结论。

Considering many uncertain factors that affect settlement of composite foundation,this paper had put forward settlement reliability analysis model of composite based on classical settlement analysis of deep-mixing pile composite foundation.Random distribution stochastic variable is mapped to stochastic variable with standard normal distribution.Optimization model for solving engineering structures reliability index is founded based on reliability index geometry significance in the normal space.Matlab's optimization toolbox is used,the reliability index and checking point had been gained together.The influence to settlement reliability of composite foundation caused by changeability of every stochastic variable is analyzed in the end.

在室内膨胀土测试试验的基础上,对邯郸膨胀土击实土样的胀缩特性进行了研究.分析了击实土样的膨胀力与初始含水量、初始干密度,以及膨胀率与压力、初始含水量和初始干密度的定量关系.结果显示:膨胀力和膨胀率均与初始含水量呈负线性相关,与初始干密度呈正线性相关;膨胀率与压力呈负指数相关.同时还根据膨胀土胀缩变形的物理机制,对各因素对膨胀土的影响机制进行了分析.

Probability analysis bases on the probability distribution of the ultimate capacity of deep mixing composite foundation. To single project, because of the datum of the bearing capacity limited, it's impossible to analyze the probability distribution of the Ultimate Bearing of Deep mixing Composite by using traditional mathematical statistics methods. This paper put forward using Monte-carlo method to analyze the ultimate bearing capacity of deep mixing composite foundation. With the local datum, the proper probability distribution is obtained through Bayes method. The index of reliability of the deep mixing composite foundation is calculated with both JC method and Monte-carlo method. The influence factors on the reliability index are also analyzed.

The paper studies the expansive characteristics of expansive soil sample in Handan area based on indoor testing experiment of expansive soil, analyses the quantitative relationship between the expansive force andthe initial moisture content the initial dry density, the expansion ratio and the pressure, the initial moisturecontent, the initial dry density,, analyses the affect mechanism every factor to expansive soil on basis of physicmechanism of expansive soil swell-shrink.

Based on the tests in the laboratory, the effects of time and pressure and initial water content on compacted expansive soils in Handan are studied. The rule that strength increased with increasing the time, decreased with increasing the pressure in water is educed. The strength decreasing velocity is large at preliminary stage, decreased gradually with increasing the time, and tending to be astable state finally. The strength increased with increasing the initial water content, and the angle of internal friction and cohesion has negative linear relation with the initial water content were found.

在现场试桩和室内模型试验基础上,探讨了嵌岩桩的承载特性和破坏模式.分析认为,在不同地质条件和设计方法下,嵌岩桩可表现为摩擦型桩或端承型桩的承载性状;嵌岩桩的破坏模式与桩岩相对刚度有关,破坏可发生的位置有:(1)桩岩界面;(2)桩周围岩中;(3)桩体本身.

运用Meyerhof理论和土的本构关系,探讨了粉喷桩侧摩阻力强化效应的形成机理。选用邯郸市3个工程的粉喷桩载荷试验资料,分析了侧摩阻力的强化效应与桩身强度、桩端土的承载力、荷载水平和桩长的相互关系,从而合理选择承载力较高的土层作为粉喷桩的桩端持力层,这对提高复合地基的承载力,减小建筑物的沉降量具有重要意义。该结论对其他类型的复合地基设计也具有借鉴作用。

In this paper, the strength theory of unsaturated soil is utilized to analyze the strength of expansive soil and its factors influenced. The consolidated undrained shear test is made by using soil sample of different water content. The relationship between the strength of expansive soil and its water content is studied. The results show that the peak value strength and stable state strength of the expansive soil are strongly affected by its water content. With increasing the water content, the strength become apparently lower. The change of coherent force is more than the change of friction angle when the water content of expansive soil is changed.

The problems of the single pile strength influenced by the organic contents, strength of pile bodies and the age are discussed through the results of the loading tests in Handan. According to the different influence factors, the method of the pile bodies strength, relative settlement and the ultimate load of piles should be individually adopted while using the load tests to determine the capacity of the piles. Which is very significant to the design and test in the real projects.

如何根据未加载至破坏的试桩资料来确定单桩极限承载力是工程界广泛关注的问题.运用灰色理论,建立了GM(1,1)模型来预测单桩极限承载力.通过对几个工程实例的对比分析,讨论了GM(1,1)模型的适用条件以及应用中注意的问题.