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本文首先介绍一种岩土自动化精密三轴压缩试验系统,并以此试验系统所得的一组实验结果为例,揭示软岩在微小应变(ε_1=10~(-2)—10~(-5))条件下所反应的应力-应变的线性关系,以及根据软岩在弹性范围内所测得的数据求出弹性模量。本文结合以往的研究成果,对软岩的弹性模量及变形系数开展分析和讨论。最后,本文将实验结果与现场测试结果相比较,从中了解两者之间的关系。 相似文献
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花岗岩中矿物相变的物性特征 总被引:3,自引:0,他引:3
本文通过对花岗岩弹性波速度、低频内耗和声发射随温度变化的实验研究,得出如下结论:波速和杨氏模具随温度的升高逐渐下降,到α-β相变点附近,波速和模量下降的梯度明显增大,并在此获得了标示石英相变的内耗峰。同时在相变点附近出现了声发射率的第二个高峰。 相似文献
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Laboratory resonant column and cyclic triaxial tests are performed to determine the dynamic response (i.e. shear modulus and damping) of chemically grouted sand. The effect of chemical grouting is evaluated as a function of shearing-strain amplitude, confining stress, cycling prestrain, number of cycles, grout type, concentration, and curing time. The test results show that the shearing-strain amplitude, grout type and grout concentration have significant effects on the shear modulus and damping ratio of the test specimens. The increased addition of sodium silicate grout, which produces stiff gels, improved the shear modulus of the test sand. The acrylate (AC-400) and polyurethane (CG5610) grout, which produces flexible (rubber-like) gels, improved the damping capacity of the sand with increasing grout concentration. The addition of chemical grout greatly reduces the effect of cyclic prestraining over untreated sands. In the case of dense sands, the reduction of cyclic prestraining is less pronounced than in loose sands, which have a higher potential for particle movement and reorientation. 相似文献
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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
780.
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