循环荷载对小叶锦鸡儿根系力学特性的影响

The Effect of Cyclic Loading on Root Mechanical Properties of Caragana microphylla

为了探究干旱、半干旱生态脆弱区植被根系承受循环荷载后的固土效能,以1.00≤d≤4.00 mm径级范围内的小叶锦鸡儿(Caragana microphylla)直根段为对象,采用TY8000伺服式强力机研究承受50次循环荷载后的根系抗拉力学特性.结果表明:1.00≤d≤2.00、2.00<d≤3.00和3.00<d≤4.00 mm直根段承受单次荷载极限力30%的循环荷载后,极限力分别为(134.42±14.17)、(285.24±27.65)、(420.24±27.36)N,较单次荷载分别增加了48.20%、42.71%、29.07%;承受单次荷载极限力70%的循环荷载后,极限力分别为(70.53±10.3)、(155.15±21.04)、(287.84±22.65)N,较单次荷载分别减少了22.23%、22.37%和11.58%.承受循环荷载后,各径级抗拉力及抗拉强度与单次荷载的差异具有统计学意义(P<0.05).试验根极限抗拉力和极限抗拉强度与其直径分别呈幂函数正相关、负相关,说明适度的循环荷载会对根系固土能力有促进作用,过度循环荷载会对根系造成损伤,降低其抗拉特性.灰色关联分析发现:直径、加载次数、加载速度均对根系力学特性产生影响.

In order to explore the efficiency of soil consolidation with vegetation roots under cyclic loading in arid and semi-arid ecologically vulnerable areas,the tensile properties of the 1.00≤d≤4.00 mm diameter straight roots of Caragana microphylla under 50 times cyclic loading were studied using the TY-8000 servo type machine.As the results show,the ultimate tension of the 1.00≤d≤2.00 mm,2.00<d≤3.00 mm and 3.00<d≤4.00 mm straight root was respectively(134.42±14.17),(285.24±27.65)and(420.24±27.36)N under cyclic loading of 30%of the ultimate force of a single loading,which increased by 48.20%,42.71%and 29.07%respectively compared with the single loading;the ultimate tension of the straight root was(70.53±10.3),(155.15±21.04)and(287.84±22.65)N,under cyclic loading of 70%of the ultimate force of a single loading,which decreased by 22.23%,22.37%and 11.58%,respectively compared with the single loading.The ultimate tension and tensile strength of each diameter class under cyclic loading were significantly different from those of the single loading(P<0.05).It is shown that moderate cyclic loading can promote the ability of the root system for soil consolidation and excessive cyclic loading will cause damage to the root system and reduce its tensile properties.The gray correlation analysis shows that the diameter,loading times and loading speed all affect the mechanical properties of the root system.