Study On Application Of Eps-sand-cement Light Weight Soil In Bridge-subgrade Transition Section

For the high moisture content, low strength and great deformation, theconstruction of expressway in soft soil area is confronted with subgrade settlement,especially in the joint between road and bridge. The “bridgehead bounce”phenomenon which generated by different deformation is heavily impact the trafficsafety. Subgrade pre-press dispose, long-and-short pile arrangement and loadexchange and decrease are the present common ways to settle this problem. Themethod of load decrease achieves the decrease of subgrade settlement and project costof dispose and maintenance by reducing the weight of filling and the additional stresson soft soil foundation. The lightweight soil construction technology is usedfrequently in load decrease method.By means of experiments and numerical simulations on mixture of constructionsand and lightweight soil, analyses and studies on mix proportion and mechanicalproperties of mixed soil generate the following solutions and achievement.1. The mixture lightweight soil is composed with raw soil, curing agent, lightmaterial and water. Construction sand, cement, globular EPS and water are used as thecomposition by theoretical analyses and experimental investigation. The physicalindexes such as density and strength are analyzed and tested on different mixproportions.(1) Lightweight soil density appeared as deceasing linear relation with thequantity of EPS, which act as the dominating influence factor. The concrete quantity,impacting energy, moisture content, sample size and maintenance conditions exert low influence on density. Therefore, the lightweight soil density can be adjusted bythe quantity of EPS in actual use.(2) Lightweight soil strength appeared as deceasing hyperbolic relation with thequantity of EPS, which act as the dominating influence factor.(3) Lightweight soil strength increase with the increasing of quantity of concrete.Comparing the variable, the influence on lightweight soil strength affected byconcrete has relationship with EPS quantity. With less EPS quantity, concrete quantityshows heavy influence on lightweight soil strength, and it can be used as one of thedominating factor. By contrast, with more EPS quantity, concrete quantity showssmall influence on lightweight soil strength, and it is not a dominating factor.2. The influence factor of settlement in road-bridge transition section is analyzedby using finite element model, and the result indicate that the density decrease oflightweight soil and the strength enhancement of down-layer soil mass are the moreavailable measures.3. The design of lightweight soil in bridge abutment is raised, including content,procedure and computational analysis method. The procedure of lightweight in bridgeabutment is set up. Some aspects of construction are determined, including mixproportion selection, job practice, procedure management and monitoring, etc.