剪切大变形条件下心墙沥青混凝土渗透特性研究OA北大核心CSTPCD

In order to study the permeability characteristics of asphalt concrete of heart wall under large shear de-formation conditions,based on a set of triaxial shear axial seepage test system developed independently,triaxial shear seepage tests with different combinations of peripheral and permeation pressures were carried out on asphalt concrete of No.70 and No.110,and the optimal model for inversion of permeability coefficient of asphalt concrete was proposed based on the global optimization algorithm.The results show that:(1)the shear expansion effect causes the opening and expansion of cracks,which increases the permeability coefficient significantly.The axial strain of two different grades of asphalt concrete reaches 8％to 30％under different circumferential pressures,and the increase of permeability coefficient reache 2 to 3 orders of magnitude.(2)The strain state and strain increment affect the permeability of asphalt concrete,and the permeability coefficient changes with the strain field.In the compaction stage,with the increase of axial strain,the volume increment ratio is negative and the permeability co-efficient decreases;in the crack development stage,the volume increment ratio is positive and the permeability co-efficient increases.(3)Perimeter pressure has a significant effect on the permeability of asphalt concrete.The axial strain corresponding to the two grades of asphalt concrete specimens reaching the impermeability safety thresh-old is small at low perimeter pressure,and shows an increasing trend with the increase of perimeter pressure.When the perimeter pressure was loaded to 1.0 MPa and the axial strain increased to 30％,the impermeability coefficient of asphalt concrete still did not exceed the impermeability safety threshold.