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691.
水泥固化铅污染土的基本应力-应变特性研究 总被引:7,自引:0,他引:7
采用水泥系固化剂,对铅污染土进行了固化处理,对固化后污染土的无侧限压缩变形特性进行了研究。试验所用的铅污染土通过人工制备而成,并考虑了不同的铅离子浓度和水泥掺量。研究结果表明,随着污染土中铅含量的变化,水泥固化铅污染土的应力-应变特性、破坏应变、变形模量值不同。铅浓度为0.01%、0.1%试样的破坏应变大于不含铅试样,且随着强度的增加、龄期的增长呈幂函数减小。韧性指数可用来定量描述铅离子浓度对固化土样韧性特征的影响程度。固化铅污染土的变形模量与其无侧限抗压强度呈线性关系,线性拟合参数与铅离子浓度和水泥掺量有关。 相似文献
692.
饱和击实黄土的动力特性研究 总被引:3,自引:0,他引:3
通过进行不同固结条件下饱和击实黄土的动三轴试验,研究了饱和击实黄土的动模量、阻尼比、动强度、动孔压及抗液化特性。研究结果表明:饱和击实黄土的动应力-应变关系符合双曲线模型,模型中参数起始动剪切模量和最大动应力与轴向固结应力间均有良好的幂函数关系,且可以对不同固结应力状态归一,固结围压和固结比对阻尼比的影响较小。动剪应力比随固结围压的增大而减小,随固结比的增大而增大。固结围压、固结比以及动应力皆对动孔压比( )与振次比关系有显著的影响,而动孔压与破坏时动孔压之比与振次比关系只受固结围压变化的影响,基本上不受固结比和动应力变化的影响,可以用幂函数关系来模拟;在均压固结条件下,当破坏振次小于等于30时,饱和击实黄土不会产生液化,而当破坏振次较大(动应力较小)时可以产生液化;在偏压固结条件下不会产生液化。 相似文献
693.
本文分析了级数形式缓和曲线切线支距坐标公式与计算偏角的相互关系,当计算偏角大于90°应使用积分公式计算缓和曲线切线支距坐标,并推导了含任意非完整缓和曲线的路线交点曲线要素公式。 相似文献
694.
为消除基座扰动对非陀螺寻北系统测量精度的影响,采用小波消噪技术对系统的输出信号进行处理。提出了利用信号在多尺度下小波变换系数中,其有用信号为平稳信号,而干扰噪声的模极大值并不随小波分解尺度增加而减少的特性,来确定基座扰动在时域上的作用点,消除影响后再进行小波变换消噪的方法。通过实验证明,该方法能有效提高系统的寻北精度,并增强系统在大幅度基座扰动下快速寻北的鲁棒性。 相似文献
695.
Summary A weathering classification for granitic rock materials from southeastern Brazil was framed based on core characteristics.
The classification was substantiated by a detailed petrographic study. Indirect assessment of weathering grades by density,
ultrasonic and Schmidt hammer index tests was performed. Rebound values due to Schmidt hammer multiple impacts at one representative
point were more efficient in predicting weathering grades than averaged single impact rebound values, P-wave velocities and
densities.
Uniaxial compression tests revealed that a large range of uniaxial compressive strength (214–153 MPa) exists in Grade I category
where weathering does not seem to have played any role. It was concluded that variability in occurrences of quartz intragranular
cracks and in biotite percentage, distribution and orientation might have played a key role in accelerating or decelerating
the failure processes of the Grade I specimens. Deterioration of uniaxial compressive strength and elastic modulus and increase
in Poisson’s ratio with increasing weathering intensity could be attributed to alteration of minerals, disruption of rock
skeleton and microcrack augmentation. A crude relation between failure modes and weathering grades also emerged.
Correspondence: Prof. T. B. Celestino, Universidade de S?o Paulo, S?o Carlos, Brazil 相似文献
696.
P. Kallioglou Th. Tika G. Koninis St. Papadopoulos K. Pitilakis 《Geotechnical and Geological Engineering》2009,27(2):217-235
The paper presents results from a laboratory investigation into the dynamic properties of natural intact and model organic
soils by means of resonant-column tests. The natural intact organic soils were sands, cohesive soils and peats with varying
content of calcium carbonate. The model organic soils were formed in laboratory by mixing kaolinite and paper pulp. The influence
of various soil parameters, such as strain level, confining stress, void ratio, plasticity index, organic content and secondary
consolidation time on shear modulus, G, and damping ratio, DT, is presented and discussed. The test results on natural organic
soils show that only high organic contents (OC ≥ 25%) have significant influence on G and DT at both small and high shear
strains. For the model organic soils, however, a significant influence of even lower values of organic content (5% ≤ OC ≤ 20%)
on G at small strains and DT at both small and high strains is observed. 相似文献
697.
Morched Zeghal 《Geotechnical and Geological Engineering》2009,27(4):549-558
This paper presents the results of a study of grain crushing in road construction and its effect on road behaviour. Sieve
analyses of field samples confirmed that grain crushing occurs during compaction of the base layer despite the good quality
of aggregates used. Laboratory testing indicated that grain crushing reduces the resilient modulus of the aggregate material
by half and increases the permanent deformations by onefold to threefold depending on the state of density and stresses considered.
Road design and analyses undertaken to delineate the effect of grain crushing on performance showed that particle breakage
yields a significant increase in rutting and longitudinal and alligator cracking of roads. 相似文献
698.
The dynamic shear modulus (DSM) is the most basic soil parameter in earthquake or other dynamic loading conditions and can be obtained through testing in the field or in the laboratory. The effect of consolidation ratios on the maximum DSM for two types of sand is investigated by using resonant column tests. And, an increment formula to obtain the maximum DSM for cases of consolidation ratio κc>1 is presented. The results indicate that the maximum DSM rises rapidly when κc is near 1 and then slows down, which means that the power function of the consolidation ratio increment κc-1 can be used to describe the variation of the maximum DSM due to κc>1. The results also indicate that the increase in the maximum DSM due to κc>1 is significantly larger than that predicted by Hardin and Black's formula. 相似文献
699.
为了克服常数模算法(CMA)收敛速度慢,稳态误差大的缺点,在分析基于可变分段误差函数的常数模盲均衡算法的基础上,提出了基于动态可变分段误差函数的常数模盲均衡算法.该算法利用均方误差(MSE)来动态调节误差函数的分段点位置,误差函数特性在均衡过程中随着MSE不断变化,使得算法误差模型与发射信号的模型不断匹配,从而具有增加收敛速度和减小稳态误差的特点.分别用混合相位水声信道和最小相位水声信道对提出的新算法进行仿真实验,结果表明:对于混合相位水声信道,新算法的收敛速度明显快于CMA,且具有更小的稳态均方误差;对于最小相位水声信道,新算法的稳态均方误差明显小于CMA,而收敛速度相当. 相似文献
700.