细粒土不均匀分布对粗粒土力学特性的影响

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。

Influence of non-uniform distribution of fine soil on mechanical properties of coarse-grained soil

In order to study the influence of non-uniform distribution of fine soil on mechanical properties of coarse-grained soil under freeze-thaw cycles, triaxial shear tests are conducted on different specimens with different distributions of fine soil undergoing different freeze-thaw cycles and confining pressures. The variation trends of position of the largest dilatancy, stress-strain behavior, initial yield strength, initial yield strain, static strength, initial yield strain and failure strain are investigated. The test results show that the position of the largest dilatancy rises with height of specimens when the fine soil mass in the upper two layers of specimens increases under the same non-uniform distribution between fine and coarse-grained particles, and the rising speed becomes faster with the increase of freeze-thaw cycles. More non-uniform distribution between fine and coarse-grained particles and higher accumulation degree of coarse-grained particles let specimens have higher brittleness, which makes degree of strain-softening more obvious. Increasing freeze-thaw cycles decreases strain-softening difference of three specimens with different fine soil masses in their upper two layers, and makes composite structure of fine and coarse-grained particles more stable. The difference of the initial yield strength or the static strength caused by the non-uniform distribution of fine soil under the same confining pressure is respectively reduced by the increase of freeze-thaw cycles. The more non-uniform the distribution between fine and coarse-grained particles, the greater the initial yield strength or static strength. The ratio of the static strength to the initial yield strength under confining pressure of 100 kPa changes unstably the freeze-thaw cycles, and that under 300 kPa changes stably with freeze-thaw cycles. The non-uniform distribution of fine soil is the most significant influence factor for the initial yield strain and failure strain, but the confining pressure has a more