Abstract
The paper presents a new type of material—foamed concrete—adopted for expansion subgrade of the expressway. Intriguingly, the irregular through shakes appear on its top. The method combining the engineering case, theoretical analysis, and numerical simulation is employed to analyze its T-shaped and tree-shaped through shake. The research indicates that when the underground water table is high, cracks are easily seen on the top of step-shape foamed concrete due to buoyancy force. Under the concentrated load effect, the maximum displacement of 27.09 mm is observed on the top of the simply supported beam when elastic modulus is 200 MPa. The maximum principle tensile stress of 0.34 MPa also occurs on the top of the simply supported beam when elastic modulus is 200 MPa and 400 MPa, which is greater than tensile strength of foamed concrete of 0.31 MPa and 0.26 MPa at 7 d and 28 d, respectively. Thus, the adoption of a simply supported beam structure fits site through crack. To avert cracks on the top of foamed concrete in high groundwater table, the antibuoyancy measures should be adopted prior to construction of the upper bearing stratum. The study has expanded the application scope of subgrade and enriched theory of foamed concrete filled in high groundwater table, providing a significant reference to similar projects.
Highlights
As a new type of material, foamed concrete was used in Japan and America in the 1980s and was later introduced to China in 2001
Theoretical analysis, and numerical simulation to the through shake on the right foamed concrete subgrade at K59 + 520∼550, the following conclusions can be drawn: (1) In the environment where groundwater table is high, the step-shaped foamed concrete subgrade is subject to minor buoyance, which causes irregular through shake on its top
(2) Under concentrated load, the displacement demonstrates a rule that, in the event of same elastic modulus, the midspan of the supported beam is larger than that of the continuous beam. e larger the elastic modulus is, the smaller the supported beam midspan is. e largest displacement 27.09 mm occurs at the top of the supported beam when elastic modulus is 20 MPa; namely, upward deflection may attain the maximum value 27.07 mm
Summary
As a new type of material, foamed concrete was used in Japan and America in the 1980s and was later introduced to China in 2001. Experts at home and abroad have conducted many studies by combining laboratory tests and engineering applications, achieving fruitful results She et al [4] indicated that foamed concrete, serving as subgrade filling of the expressway, boasts favorable loading capacity and sedimentation reduction. E paper intends to analyze the cause of crack at the top of foamed concrete and proposes the applicable condition of foamed concrete subgrade through two key factors such as inverted step and underground water, offering important references for design and construction of other similar projects. 2. Example of Through Shake in Foamed Concrete Subgrade e design requires that compressive strength of foamed concrete at this section be no less than 1.0 MPa. e foamed concrete is made using normal Portland cement P.O42.5, water, and high-performance foaming agent (liquid foam) per certain proportion.
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