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为了研究冻融循环条件下细粒土的不均匀分布特性对粗粒土力学特性的影响,对不同冻融循环次数、冻结温度、围压条件下的含有不同细粒土分布的粗粒土进行常规的静三轴剪切试验,研究冻融循环后具有不均匀细粒土分布的试样的最大剪胀位置、应力–应变关系曲线、起始屈服强度、起始屈服应变、静强度、破坏应变变化规律。研究结果表明,在相同的细颗粒与粗颗粒不均匀分布的条件下,试验后试样的最大剪胀位置随着试样上两层中细粒土含量的增加而沿着试样高度上升,随着冻融循环次数的增加,最大剪胀位置的上升速率是不断增加的。细颗粒与粗颗粒不均匀分布的程度越高,尤其是粗颗粒的富集程度越高,试样的脆性越高,试样的应变软化程度越明显。冻融循环次数的增加,降低了粗、细颗粒较均匀分布的3种试样的应力–应变软化程度的差异性,即冻融循环次数的增加可以使粗颗粒和细颗粒的组合结构趋于稳定。在相同的围压条件下,冻融循环次数的增加削弱了因细粒土不均匀分布而导致的起始屈服强度的差异性和静强度的差异性。试样中的粗颗粒和细颗粒分布越不均匀,试样的起始屈服强度和静强度越大。当围压为100 k Pa时,静强度与起始屈服强度的比值随冻融循环次数波动较大,当围压增加到300 k Pa时,比值随冻融循环次数的波动较为平缓。细粒土不均匀分布是起始屈服应变和破坏应变的最显著性影响因素,但是围压对破坏应变的影响程度明显大于围压对起始屈服应变的影响程度。细粒土不均匀分布对破坏应变影响的显著性明显小于它对起始屈服应变影响的显著性。
In order to study the effect of the uneven distribution of fine-grained soil on the mechanical properties of coarse-grained soil under freezing-thawing cycles, the effects of different freeze-thaw cycles, freezing temperature and confining pressure on the coarse grained soil with different fine grained soils Conventional static triaxial shear tests were carried out to study the maximum dilatancy position, stress-strain curve, initial yield strength, initial yield strain, static strength and failure of specimens with uneven fine-grained soil distribution after freeze-thaw cycles Strain changes. The results show that under the condition of the same fine particles and coarse particles are not uniformly distributed, the maximum dilatancy position of the sample increases along with the increase of the content of fine-grained soil in the two layers of the sample, With the increase in the number of freeze-thaw cycles, the rate of increase of the maximum dilatancy position is increasing. The higher degree of uneven distribution of fine particles and coarse particles, especially the higher the degree of enrichment of coarse particles, the higher the brittleness of the sample, the more obvious the strain softening degree of the sample. The increase of the number of freeze-thaw cycles reduced the difference of stress-strain softening degree of the three kinds of samples, in which coarse and fine particles were distributed uniformly. That is, the increase of the number of freeze-thaw cycles can make the combination structure of coarse particles and fine particles tend to stable. Under the same confining pressure, the increase of freeze-thaw cycles reduced the difference of initial yield strength and the difference of static strength due to the uneven distribution of fine grained soil. The more uneven distribution of coarse particles and fine particles in the sample, the greater the initial yield strength and static strength of the sample. When the confining pressure is 100 kPa, the ratio of static strength to initial yield strength fluctuates greatly with the number of freeze-thaw cycles. When the confining pressure increases to 300 kPa, the ratio fluctuates more gently with the number of freeze-thaw cycles. Uneven distribution of fine grained soil is the most significant influencing factor of initial yield stress and failure strain, but the effect of confining pressure on failure strain is obviously greater than that of confining pressure on initial yield strain. The significance of the effect of the uneven distribution of fine grained soil on the failure strain is significantly less than its effect on the initial yield strain.