砂岩崩解岩改性弱膨胀性岩土试验研究

Experimental Study on Weak Expansive Rock and Soil Modified by Disintegrated Sandstone and Other Rock

膨胀性岩土因其胀缩性、多裂隙性使分布其上的水利、交通工程遭受破坏,充分利用当地料源结合一定掺量水泥是处理膨胀性土的有效方法之一。选取某地区弱膨胀岩土,采用开挖弃料砂岩崩解岩物理改性弱膨胀性岩土,基于自由膨胀率试验提出最优掺量配比,并开展物理改性料和掺水泥改性后土样的基本物性试验及膨胀特性试验,揭示了改性土的膨胀变形发展规律。试验结果表明:(1)砂岩崩解岩物理改性弱膨胀土和泥岩崩解岩的最优掺量配比分别为3∶7和5∶5;(2)两种掺和料最优配比96%压实度下渗透系数k≤10^(-4)cm·s^(-1),掺3%水泥改性后渗透系数k≤10^(-5)cm·s^(-1);(3)物理改性土当上覆压力在6.25 kPa时膨胀率低至2.0%以内,掺3%水泥改性后无荷膨胀率低至0.2%,改性土的膨胀变形明显减小。

The water conservancy and transportation projects in the expansive soil and rock formations are frequently damaged due to the expansion,contraction and multi cracks in these soil and rock formations.To fully utilize the local waste material resources mixed with a certain cement ratio is one of the effective methods to mitigate expansive soils and rocks.The weak expansive rock and soil in an area are selected as the study site,and the weak expansive rock and soil are physically modified by the excavated waste disintegrated sandstone and other rocks.Based on the free expansion rate test,the optimal mixing ratio is proposed,and the basic physical property test and expansion characteristic test of the soil samples modified by the physical modified material and cement are performed to evaluate the expansion deformation of the modified soil.The test results show that:(1)the optimal mixing ratio of the physical modified weak expansive soils with the disintegrated sandstone rock and mudstone is 3:7 and 5:5 respectively;(2)The permeability coefficient K≤10^(-4)cm/s under 96%compaction and the permeability coefficient K≤10^(-5)cm/s after the modification with 3%cement;(3)When the overburden pressure of the physically modified soil is 6.25 kPa,the expansion rate is less than 2.0%.After being modified with 3%cement,the unloaded expansion rate is less than 0.2%,and the expansion deformation of modified soil is significantly reduced.