Papers by Keyword: Triaxial Shear Test

Abstract: The subgrade of the most roads is easy to be of instability under the cyclic loading action of the vehicles with the soil unsaturated. The main idea of this paper is that researching the unsaturated red clay which is common in the subgrade building of Jiangxi province with the pressure plate test and triaxial shear test. And the main equipments are the pressure plate apparatus and triaxial shear apparatus. In the research, c,φ value of the unsaturated red clay under different confining pressure and matrix suction are obtained and it can be shown in the tests that with the same matrix suction, while clay content of the clay soil sample is small its volumetric water content is small; and with the same volume moisture content, with small clay content matrix suction of the soil sample is small similarly. At the same time, we found that within the low substrate suction range, with the change of the soil sample moisture content bigger and the smaller the clay content, the influence the increase of matrix suction on the volumetric moisture content is smaller; with the same clay content in soil samples, the bigger the matrix suction the greater the value of c, φ of the unsaturated red cohesive soil ;with the same matrix suction, the smaller the clay content of the soil, the greater the value of c and the smaller the value of φ.

Abstract: In order to obtain the influencing factors and behavior of the intrinsic length of clay in Tianhe District of Guangzhou, different specimens are fabricated by the mixing clay and quartz sand in Tianhe District. Using the triaxial shear test results, the intrinsic lengths of different samples are determined. The results show that the liquidity index of matrix has little effect on the intrinsic length. The intrinsic length increases linearly with increasing reinforcing particle content. The larger the content is, in reinforcing particle the larger the decrease is in intrinsic length. The intrinsic length decreases with increased reinforcing particle size.

Abstract: Three kinds of frozen soils were tested for artificial ground freezing (AGF) project in the tunnel construction of Stonecutters Island Sewage Treatment Works, Hong Kong. Triaxial shear test was conducted to obtain shear strength of frozen soils. From the test, Mohr circles and their envelopes were obtained. According to Mohr circles, shear strength of the three soils was gained. Comparing the three soils, we found the potential weaken layer which might cause failure in the construction. All the parameters obtained can be used in design and construction of AGF practice.

Abstract: This paper mainly concerns the non-linear strength characteristics of the loess. A series of consolidated undrained triaxial tests(CU test) and consolidated drained triaxial tests (CD test) of normal consolidation and over consolidation loess specimens are carried out by using the normal triaxial apparatus of strain control. The stress-strain relationship curves and strength characteristics of loess are investigated and analyzed. The results show that the stress-strain relationship obtained by CU tests appears strain softening, while the stress-strain relationship for CD tests appears strain hardening. Different failure modes have different stress-strain relationships. Furthermore, the results also show that the peak strength, residual strength and residual strength ratio change with the different confining pressure. Based on the triaxial shear tests of normal consolidated loess, the influences of over-consolidated loess on the stress-strain relationships and strength characteristic are discussed. Several conclusions obtained in this paper can be referenced for the loess experimental study.

Abstract: General triaxial CD and CU tests are conducted to properly understand mechanical property of cement-soil. Experiment data indicate that: (a) different stress paths have some but little influence on the strength of cement-soil; (b) under low confining pressure, cement-soil is similar to highly overconsolidated soil with shear dilatancy property; but under high confining pressure, it is similar to slightly overconsolidated soil; (c) its residual strength increases linearly with the increase of confining pressure, and the residual strength of CD test is greater than that of the CU test; (d) the ratio of residual strength to peak strength increases with the increase of confining pressure, while its increasing rate decreases; (e) the effective stress envelope of CU test and that of CD test are basically identical.

Abstract: The conventional triaxial compression(CTC), triaxial compression(TC) and reduce triaxial compression(RTC) of ordinary loess in Xi，an Ba He was conducted with GDS stress path tests and the strength behavior and deformation capacity of loess was studied. The experimental results showed that the larger the initial moisture content, the smaller the shear strength. The strength characteristic of loess varied under different stress path. Relationships between σ and ε was strain hardening model. The peak strength of CTC is larger than that of TC and the peak strength of RTC was smaller.

Abstract: With uniaxle penetration test method and Triaxial Shear method test, the shear strengths for asphalt mixture were analyzed. It turns out that the result of triaxial shear test is a little conservative than that of uniaxle penetration test. Then reasonable structure factor for shear strength should be considered by uniaxle penetration test. Uniaxle penetration tests at different temperatures revealed there were a linear correlation between shear strength and temperature.The asphalt was not the main fator of shear strength at high temperature.

Abstract: Strength characteristics play an important role in mechanic behavior of cement-soil. Laboratory tests on cement-soil with 12% cement ratio and 28 d curing time are conducted by using a new multifunctional triaxial apparatus under fixed spherical pressure condition. Seven series spherical pressures are designed to apply, namely 300 kPa, 400 kPa, 500kPa, 600 kPa, 800 kPa, 1000 kPa, and 1200 kPa. At the same time, seven series consolidation pressures are taken into accounted. Tested data show that: (1) the stress-strain curve of cement-soil is characterized by strain softening, and the soften rate is related to confining pressure; (2) shrinkage or dilatancy of cement-soil volume strongly depend on the value of loaded spherical pressure; (3) failure curve of cement-soil is approximately a line and it agrees with the Mohr-Coulumb criterion. The result of this paper is helpful to the numerical analysis and practical engineering design of cement-soil foundation structures.

Abstract: The consolidation coefficient is the important parameters for soft soil foundation to predict its consolidation settlement. At present, one-way compression test is mainly used to study consolidation process and consolidation coefficient of soft soil. For saturated soft soil in marsh, through triaxial shear test, the dissipation of pore water pressure and consolidation process can be observed during the course of soil sample drainage. This study got test result bellow through above triaxial test. Firstly, pore water pressure has hysteresis effect during the consolidation process, and the reason for this is analyzed. Secondly, consolidation degree in different consolidation time can be got according to the change of discharged water volume. Thirdly, according to Terzaghi consolidation theory, consolidation coefficients can be got under different consolidation pressures. Consolidation coefficient first increases with the increasing of consolidation degree, when consolidation degree is between 40% and 80%, saturated soft soil has larger consolidation coefficient, consolidation coefficient of saturated soft soil in marsh is between 2Ч10^-4 cm² / s and 10Ч10^-4cm² / s.

Abstract: The soil-water characteristic curve (SWCC) is one of the major research subjects in unsaturated soil mechanics. To study the influence of deviatoric stress on the SWCC of an unsaturated soil, a series of triaxial drained shear tests by controlling constant net mean stress and suction were conducted. It was found that the SWCC was dependent on deviatoric stress. A unified SWCC equation was proposed including not only water content and suction, but also net mean stress and deviatoric stress.