换填黏性土料工程特性试验研究

南水北调中线一期工程总干渠膨胀岩（土）试验段工程潞王坟段的渠坡处理方式之一是换填黏性土料处理措施，通过开展物理性试验、击实试验、膨胀特性试验和原位测试等来了解换填黏性土料的工程特性。研究表明：（1）换填黏性土料颗粒组成差异较大，以砂粒和粉粒为主，其次为砾，黏粒和胶粒成分较少，其级配一般；（2）轻型击实条件下，换填黏性土料最优含水率为17.7 %，对应的最大干密度为1.71 g/cm3；重型击实条件下，换填黏性土料最优含水率为18.4 %，对应的最大干密度为1.87 g/cm3；（3）换填黏性土料的相对密度为2.7，液限在37.6 %～38.7 %之间，塑限在17.1 %～19.2 %之间，塑性指数在19.4～21.2之间，属于低液限黏土；（4）当取样深度在0.0～3.5 m之间时，换填黏性土料的自由膨胀率在40.0 %之内，无膨胀潜势；当取样深度在3.5～4.5 m之间时，换填黏性土料的自由膨胀率在42.0 %～76.0 %之内，具有中弱膨胀潜势；（5）换填黏性土料的旁压模量 、侧胀模量 随深度变化不明显，当含水率变化时有部分成果有随含水率增加而模量参数降低趋势。该成果为换填黏性土料在南水北调中线一期工程总干渠膨胀岩（土）试验段工程中的应用提供了科学依据。

Experimental study of engineering property of replaced-backfilling clay

One of the slope treatment measures is the replaced-backfilling clay treatment in the Luwangfen test region of middle-route of South-to-North water division project. The engineering property of replaced-backfilling clay is studied by physical test, compaction test, expansive property test and in-situ test. Studies show that: (1)the diversity of particle component of it is obvious, in which sand grain and silt are dominant, gravel is lesser, cosmid and colloidal particle are least;(2)the optimal water content of replaced-backfilling clay is 17.7 % with the corresponding maximum density of 1.71 g/cm~3 under the condition of light compaction, the optimal water content is 18.4 % with the corresponding maximum density of 1.87 g/cm~3 under the condition of heavy compaction;(3)the specific gravity of replaced-backfilling clay is 2.7, liquid limit is between 37.6 %-38.7 %, plastic limit is between 17.1 %-19.2 %, plasticity index is between19.4-21.2, therefore, it belongs to low liquid limit clay;(4)when the sample of replaced-backfilling clay is selected within the depth of 3.5 m, the free expansive rate is within 40.0 %, which means there is no expansive potential; when the sample is selected between the depth of 3.5-4.5 m, the free expansive rate is between 42.0 %-76.0 %, which means there is middle or weak expansive potential; (5)there is no obvious relation between E_m(E_D) of replaced-backfilling clay and depth, but the module parameters of it has the decreasing tendency with the increase of water content. The result provide scientific reference for the application of replaced-backfilling clay to the middle-route of South-to-North water division project.