基于现场试验的刚-柔性基础下膨胀土变形特性研究

Study on Deformation Characteristics of Expansive Soil under Rigid and Flexible Foundations Based on Field Tests

为研究膨胀土地基的膨胀变形响应规律,结合云桂客运专线建设,在弥勒中-强膨胀土区域选取典型工点,开展刚性基础(多压板荷载)与柔性基础(低路基)下膨胀土地基现场浸水试验,对比分析浸水后刚性和柔性基础下膨胀土地基的膨胀变形差异。试验结果表明:在较小荷载下,刚性基础与柔性基础下地基均产生明显的膨胀变形,膨胀变形量与上部荷载近似呈双曲线关系,前者的极限膨胀量约为后者的85%。对云桂客运专线试验段路基的长期监测试验表明:在自然条件下,路基较低时,地基相对膨胀量变化值随路基高度的增加而减小;路基高度超过5m时,其相对膨胀量变化值趋近于0,自然降雨对超过该填高的中-高路基下膨胀土地基的膨胀变形几乎无影响。

To study the response of swelling deformation of expansive soil ground, considering the construction of Kunming-Nanning Railway, typical fields were selected in Mile medium-strong expansive clay region, where field soaking tests on expansive soil ground under rigid foundation（multi-plate loading） and flexible foundation （low subgrade） were carried out. The differences of swelling deformation of expansive soil ground after soaking under rigid and flexible foundations were analyzed. Test results show that under smaller load, significant swell-ing deformation occurs in the ground under both rigid and flexible foundations. The relationship between swell-ing expansion and upper load is similar to hyperbolic change. The ultimate expansion under rigid foundation is 85% of that under flexible foundation. Through long-term monitoring tests of the subgrade of the test section of Kunming-Nanning Railway, under natural conditions, under low subgrade, the relative expansion of expan-sive soil ground decreases with the increase of subgrade height. In the case of subgrade height at more than 5 m, the relative expansion is close to zero and rainfall makes no difference to swelling deformation of the ex-pansive soil ground under high subgrade which exceeds the critical height.