CFG桩的几种方法综合检测

采用CFG桩处理的地基,具有承载力提高幅度大、工后地基变形小以及施工方便快捷等特点。本文通过比较几种检测方法的适用性,提出了几种方法的检测次序、侧重点和局限性,从而总结出,几种方式配合起来,综合使用,可以对CFG桩进行经济、有效且准确的检测。     

冻土中锥型桩模型试验研究及有限元分析

通过冻土中锥型桩室内模型试验研究得出冻结土体中锥型桩承载力特征:Q-S曲线未发现“台阶”现象,也不存在陡降段,其破坏形式接近于渐进型。对现有冻土流变模型的分析,提出了用非线性牛顿体替代线性牛顿体,建立了改进的西源本构模型;并将改进的西源本构模型成功地添加到ADINA软件平台中。采用改进的西源本构模型对冻土中锥型桩室内模型试验进行了有限元数值仿真,模型试验结果和有限元计算接近,表明:采用有限元数值方法可为寒区冻土中锥型桩设计和施工提供参考。     

Grapho-analytical processing of results of static testing of soils by cast-in-place piles and cone penetration

An engineering method is proposed for enhancement of the reliability of reported documentation of design-survey operations using linear approximation of standard soil-test data derived from piles and cone penetration.     

Mechanical properties of frozen soils

The modern state and basic trends in research on the behavior of frozen soils as a natural multicomponent and multiphase system under load are analyzed in this study. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 2–8, March–April, 1996.     

冻土动强度特性试验研究

在围压为0.3～16 MPa,频率为2 Hz,温度为-4和-6℃条件下,通过一系列恒应力幅循环动荷载试验,发现冻土动强度的变化不仅跟破坏振次的大小有关,而且与围压、循环荷载作用下土体吸收的有效能量(损失能)之间也存在一定关系。根据损失能获得试样温度的变化,将冻土动强度与温度直接联系起来,表明振动荷载作用下损失能累积造成的温度额外升高是控制冻土动强度变化特性的主要因素之一。     

Results of field tests of piles in permanently frozen ground

Conclusions 1. To estimate the bearing capacity of piles and to determine the deformation characteristics of soils it is necessary to conduct comprehensive pile tests on plots with the same frozen-ground conditions.2. Pile tests should be conducted before the appearance of the second region of continuous deformations. For structures allowing considerable deformations this will permit increasing the bearing capacity, taking it to be equal to the value at which the jog of the soil consolidation under the pile point ends.3. Calculation of pile foundations with respect to the second limiting state permits a substantial increase of the design bearing capacity of piles, which ultimately leads to a reduction of construction costs.4. The use of the accelerated test method with the obtainment of the experimental values of the conversion factor to long-time strength permits a considerable reduction of the test period.5. The data obtained in pile tests permits developing more economical designs.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 35–36, September–October, 1977.     

Thaw-induced deformation properties of frozen soils

Materials derived from laboratory study of thaw-induced settlement of soils residing in the central portion of the Bovanenkovsk gas and oil field (GP-2) are presented. The dependence of the thaw-induced settlement of the soils on various parameters (W, ρ, i _i , i _tot , etc.) was investigated. Experimental thaw-induced settlements are compared with those calculated from different relationships.