聚丙烯纤维改良土抗冻性能研究

Study on Frost Resistance of Polypropylene Fiber Modified Soil

为确保聚丙烯纤维改良土在冻融条件下具有良好的力学强度,研究了冻融次数、纤维掺量,以及长度对纤维改良土力学强度的影响规律.结果表明:当冻融作用进行到15次后纤维改良土力学强度基本不再变化,与冻融0次力学强度相比,冻融15次后抗剪强度和抗压强度分别平均降低了10.7%,12.1%;同一纤维长度与冻融次数下,冻融作用下0.3%纤维掺量改良土力学强度最大,较0.1%纤维掺量改良土力学强度,抗剪强度和抗压强度分别至少提高了3.2%,79%;冻融作用下纤维改良土抗压强度随纤维长度增加逐渐提高,且纤维长度从9 mm增加至12 mm时,改良土抗压强度提高了7.6%.另外,纤维掺量<0.3%时,纤维改良土抗剪强度在纤维长度9 mm处取得峰值.对此,建议采用聚丙烯纤维改良土冻融作用15次后力学强度作为强度设计指标,且纤维改良土最佳聚丙烯纤维掺量为0.3%、长度为9 mm.

In order to ensure good mechanical strength of polypropylene fiber improved soil under freeze-thaw conditions,the influence of freeze-thaw times,fiber content and length on mechanical strength of fiber improved soil was studied.The results show that the mechanical strength of the fiber-modified soil basically does not change after the freeze-thaw action is carried out for 15 times.Compared with the mechanical strength after freezing and thawing for 0 times,the shear strength and compressive strength decreased by 10.7%and 12.1%respectively after freezing and thawing for 15 times.Under the same fiber length and freeze-thaw times,the mechanical strength of the soil improved by 0.3%fiber content under freeze-thaw action is the highest,and compared with 0.1%fiber content,the shear strength and compressive strength are increased by at least 3.2%and 79%respectively.Under freeze-thaw action,the compressive strength of fiber-improved soil gradually increases with the increase of fiber length,and when the fiber length increases from 9 mm to 12 mm,the compressive strength of improved soil increases by 7.6%.In addition,when the fiber content is less than 0.3%,the shear strength of the fiber-improved soil reaches the peak at the fiber length of 9 mm.Therefore,it is suggested that the mechanical strength of polypropylene fiber-modified soil after 15 times of freeze-thaw action should be taken as the strength design index,and the optimum polypropylene fiber content of fiber-modified soil is 0.3%and the length is 9 mm.