中低压缩性黏土地基沉降变形特性试验研究

Experimental investigation on settlement deformation behavior of clay ground with medium-low compressibility

以宁安城际铁路安庆试验工点长江高阶地区冲积成因中低压缩性黏土为研究对象,进行了一系列土工试验、原位测试和现场填筑试验.对中低压缩性黏土的物理力学指标进行了整理分析,探讨了试验方法对沉降计算指标取值的影响;基于现场填筑试验,对中低压缩性黏土地基的总沉降、分层沉降、孔隙水压力和侧向位移进行了分析.结果表明:该中低压缩性黏土具有较好的工程特性和强超固结特性,取样扰动对土工试验结果影响显著,推荐采用静力触探试验获取沉降计算指标;路堤荷载下地基以浅层弹性变形为主,孔隙水压力和侧向位移监测结果均表明地基内部排水固结现象不明显,路堤荷载主要由土粒骨架承担.

A series of soil tests,in-situ tests,and field experiments were conducted focusing on the alluvial clay with medium-low compressibility（CMLC）distributing at the high fluvial terrace of Yangtze River,sampled from the test field in Anqing along Ning＇an high-speed railway.Physico-mechanical properties of the CMLC were studied and the effect of test methods on parameters of settlement calculation was investigated.Meanwhile,the total settlement,layer settlement,pore water pressure,and lateral displacement were all studied based on field measurements.Results show that the CMLC is of good engineering properties and strong overconsolidation characteristic.Obvious effect of sampling disturbance on the soil test results is observed.Static cone penetration test is recommended to obtain the parameters of settlement calculation.The ground settlement is dominated by elastic deformation of shallow strata under embankment load.Field measurements of pore water pressure and lateral displacement indicate that drainage consolidation is not obvious and the embankment load is mainly undertaken by the soil particle skeleton.