Experimental Study On The Mechanical Properties Of Lime Modified Fully Weathered Red-mudstone

According to the national planning for the Chengdu-Chongqing twin-city economic circle,the Chengdu-Chongqing region is to be built into a twin-city economic circle on rails,with a number of new high-speed railway trunk lines planned in the coming years.The Chengdu-Chongqing region is widely distributed with a large amount of red-layered mudstone,and the planned construction of several high-speed railways,such as the Chengdu-Chongqing High-speed Railway Central Line,is an important part of the multilevel rail transportation in the Chengdu-Chongqing region twin-city economic circle,which inevitably has to cross the red-layered mudstone area.If the red-layered mudstone is used as roadbed filler by lime,it can expand the range of filler selection and reduce the red-layered disposal.In order to study the applicability of the red-layered mudstone and lime improvement as roadbed filler in the Chengdu-Chongqing area,the one-dimensional deformation test,unconfined compressive strength test and direct shear test were used to study the mechanical properties of the red-layered mudstone before and after lime improvement,and to explain the mechanism of lime improvement from a microscopic perspective.(1)To study the influence of dry density on the one-dimensional deformation characteristics of compacted red mudstone,a prediction model of loaded swelling rate is proposed,the influence of hydraulic path on swelling force is elucidated,and the law of influence of lime modification on the one-dimensional deformation characteristics of red mudstone is clarified.(2)The effect of lime modification on the unconfined compressive strength of red mudstone is clarified,and the effect of wet and dry cycles on the unconfined compressive strength of lime modified red mudstone is elucidated,and the red mudstone can be used as the filler of the embankment body of passenger and freight railway according to the specification evaluation,and the modified red mudstone can be used as the sub-bed filler of passenger and freight railway/high-speed railway.(3)The influence of dry density and water content on the strength,brittleness and shear swelling of red mudstone is clarified,and the interaction between the brittleness and shear swelling of red mudstone is revealed.(4)The improvement mechanism of lime on red mudstone is revealed: as the lime mixing dissolves the montmorillonite in the red mudstone,the lime improvement can effectively inhibit the swelling of the red mudstone,in addition,the cementation products such as calcium alumina formed by lime hydration fill in between the pores of soil particles,enhance the cementation between soil particles and form a three-dimensional mesh structure,so the strength of the red mudstone after lime improvement is significantly increased,and the resistance to deformation is significantly The strength of the red mudstone is significantly increased and its resistance to deformation is significantly enhanced.