Centrifugal Model Test Study Of Foamed Lightweight Concrete For Highway Subgrade Widening

As for a new type of material, cause of its porous, light weight, adjustable property of density and strength, well construction property, durability, environmental protection characteristics, solidification after hardening and other excellent characteristics, foamed lightweight concrete can be used to solve The problem of uneven settlement of highway widening roadbed. So, it has a good engineering application prospects.Aiming at the technical problems encountered in expressway widening project, using the new type of material, carried out a series of research on foamed lightweight concrete by Indoor test, numerical simulation and centrifugal test. The main research contents and achievements are as follows:l)By unconfined compressive strength test, study the relationship between wet density and stress-strain behavior, unconfined compressive strength, elastic modulus of the foam lightweight concrete. With the increase of wet density, the change mode of the normalized stress-strain curve is gradually transition from the point yield to the oscillating yield, the compressive strength and elastic modulus also increased gradually. The compressive strength of foamed lightweight concrete which wet density is 700kg/m5 can reach more than 1.0MPa, could meet the requirements of the highway widening filler standards. The above mechanical parameters provide reliable basis for settlement prediction, stress calculation, numerical simulation and so on.2)by numerical analysis method, study on the working mechanism of highway subgrade widening in all phases of the new and old roadbed mechanical performance. The calculation shows that, because of the light weight characteristics, foamed lightweight concrete can effectively improve the stress conditions of the new subgrade section, reduce additional settlement, decrease new and old roadbed differential settlement, reduce the lateral displacement of foundation soil, have a smaller pore pressure disturbance and consolidation settlement, improve the stress state of the lower soil.3)Use centrifuge test technology, reproduce the condition of numerical simulation, simulating the process of many years’ subgrade settlement. The data show that the settlement of foam lightweight concrete similar to ordinary filler. Overall, its performance like concrete structure, in terms of settlement after construction, widening subgrade rotates around the old subgrade slope similar rigid body, its steady speed is more rapid. Because of the influence of its self-weight load and section structure, soil pressure in foundation soil which is under the widened section is significantly reduced. The influence of the old roadbed area is very weak also, the overall stability of the structure is good.4)Through those above comparison experiment of formed lightweight concrete, can find that, it has technical advantages in the highway subgrade widening. Formed lightweight concrete can be very good to deal with the new and old roadbed differential settlement, reduce the lateral displacement caused by subgrade widening, improve soil mechanical characteristics decrease the pore pressure disturbance of soil, improve the overall stability of the structure, is a kind of excellent performance of Widening Roadbed filler.