膨胀性混合土路用性能试验研究

Experimental Study on Road Performance of Expansive Mixed Soils

路桥过渡段因差异沉降易出现“桥头跳车”路面病害,为了探讨回填膨胀性混合土对治理路桥过渡段差异沉降是否有效,通过无侧限抗压强度、CBR、直剪、渗透和膨胀试验,研究了膨胀性混合土的路用性能。结果表明:1)在掺量20%、龄期28 d和含水率8%条件下,膨胀性混合土的无侧限抗压强度大于0.80 MPa;2)最佳含水率8%,龄期7 d,CBR值均达到20%及以上,满足路基承载力要求;抗剪强度特性与弱胶结粉砂土类似,内摩擦角φ=32.8°,内聚力c=5.4 kPa;3)渗透系数约为1×10^(-4) cm/s,渗透性能较好;4)约10 d后膨胀性混合土的膨胀率就能趋于稳定,之后不会发生体积收缩或膨胀。研究证明膨胀性混合土路用性能达到规范要求标准,可用于修复路桥过渡段路面病害。

The pavement disease such as bridge bump occurs due to differential settlement in the road bridge transition.In order to explore the validity of backfills with expansive mixed soils in the road bridge transition to deal with the differential settlement,the road performance is investigated by means of experimental study with a series of tests on expansive mixed soils,such as unconfined compressive strength,CBR,direct shear,permeable and expansive tests.Test results show that:1)the unconfined compressive strength of expansive mixed soils is over 0.80 MPa with expansive fills of 20%,water content of 8%when the curing age is 28 d;2)the value of CBR is over 20%and meets the bearing capacity requirement of subgrade when optimum moisture content is 8%and the curing age is 7d,and the shear strength of expansive mixed soils is similar to that of cemented silt sands,and the internal frictional angleφis 32.8°,and cohesion c is 5.4 kPa;3)the permeability coefficient is approximately 1.0×10^(-4) cm/s which exhibits a good permeability;4)the expansive rate of expansive mixed soils approaches a constant about 10 days later and after that there is no more shrinkage and expansion.It is proved that the pavement performance of the expansive mixed soil meets the standard requirements and can be used to repair the pavement diseases in the transition section of the road and bridge.