膨胀岩击实样胀缩特性试验研究

选取泥灰岩和黏土岩 2 种代表性的膨胀岩，通过大尺寸的胀缩特性试验，研究了膨胀岩击实样的胀缩特性，及其与起始含水率、压实度的关系。成果表明：随起始含水率增大，膨胀岩的无荷膨胀率呈较好的线性递减关系；压实度越大，无荷膨胀率越大，且随起始含水率的减小，压实度对膨胀率的影响呈增强的趋势；在相同压实度下，起始含水率低于塑限值时，起始含水率变化对线缩率的影响很小，随起始含水率增大，线缩率开始呈较平缓的线性增大；当起始含水率达到塑限值附近后，起始含水率变化对线缩率的影响开始显著增强；在相同起始含水率下，起始含水率低于塑限值时，压实度对线缩率的影响很小，随压实度增大，线缩率呈较好的线性递减；当起始含水率达到塑限值附近后，压实度对线缩率的影响略微增强。膨胀岩的收缩系数和体缩率与线缩率的规律基本一致。

Experimental Research on Expansion and Shrinkage Characteristics of Compacted Expansive Rock

For the research of expansion and shrinkage characteristics of expansive rock, two typical expansive rocks, namely marl and clay rock , of Xinxiang section of the Mid-route of South-to-North Water Transfer Project are selected to perform a large-size test of expansion and shrinkage characteristics for the disturbed sample which has been screened through a 20mm sieve. A statistic analysis is conducted from test results of the undisturbed sample of marl and clay rock in this paper, and its emphasis is to research the regularity relationship among the initial water content, compaction degree and swelling-shrinking characteristics of the reconstituted samples selected from the expansive rock in Xinxiang. And the test results show that: with the increase of the initial water content, the load-less expansion rate of expansive rock presents a good linear decreasing relationship; with a higher compactiondegree and load-less expansion rate and a decreasing initial water content,the impact of compaction degree on the expansion rate presents an increasing trend; with the same compaction degree, the effect of initial water content variation on the shrinking ratio is little when the initial water content is lower than the value of plastic limit, and the shrinking ratio initially presents a gently linear increase as the initial water content grows; when the initial water content is near the plastic limit value, the impact of initial water content variation on the shrinking ratio is enhanced significantly; with the same initial water content which is lower than the value of plastic limit, the influence of compaction degree on shrinking ratio is little , however, as the compaction degree increases, the shrinking ratio presents a good linear decreasing relation; the impact of compaction degree on the shrinking ratio is reinforced slightly when the initial water content is near the value of plastic limit. The regularity of shrinkage coefficient and volume contraction ratio of the expansive rock is almost the same as that of the shrinking ratio.