红山窑膨胀红砂岩地基处理方案研究

Study on foundation treatment scheme of expansive red sandstone in Hongshanyao

经野外地质勘探,红山窑风化红砂岩初判为膨胀岩,为寻求技术上安全可靠而又经济合理的设计施工方案,对该膨胀岩进行了膨胀变形特性和力学性质试验,研究其随含水量变化时的膨胀变形特性和力学性质指标。试验结果表明:膨胀应变在较短时间内完成总膨胀量的90%左右,随着时间的增长,最终趋于稳定;在不同初始含水率至吸水饱和时,初始含水率越低,吸水达到饱和时产生的膨胀力越大,初始含水率越高,吸水达到饱和时产生的膨胀力越小。且含水率ω∈[0%,6%]至饱和是该膨胀岩膨胀力的显著增长点。根据试验结果提出如下地基处理方案:对位于中风化层的红砂岩地基,只采用控制含水率(不低于6%),限制膨胀力(小于40kPa)的方法;对部分位于全风化岩层上的地基可采取换填土处理。

Through the field geological exploration the weathering red sandstone in Hongshanyao is considered as expansive rock.In order to seek the design and construction scheme which is safe and reliable in technology and economic and reasonable,the tests for the characteristics of swelling deformation and the mechanical properties of expansive rock are carried out,and the variation of the characteristics and properties with water content is studied.The test results show that： the expansion strain is finished the 90% of the total expansion strain in a shorter time,and the expansion strain finally reached the steady value with time increasing.The lower the initial water content is,the larger the expansive force produced by water absorption in the saturated state is.The larger the initial water content is,the lower the expansive force is.The significant increasing point of the expansive force of the rock is moisture content ω∈ to saturation.Based on the test results,the foundation treatment scheme is presented,and scheme is used to the red sandstone foundation located in the middle weathered layer.The moisture content only is controlled in no less than 6%,and expansive force is controlled in less than 40kPa.For the red sandstone foundation located in completely decomposed weathered layer,the treatment of replacing and filling earth could be used.