Abstract
This paper described a continuous load one-dimensional K0 consolidation apparatus developed and improved, conducted an axial cyclic loading and unloading test of saturated soft clay. It can be known from the experimental comparison that during the unloading period, a stress strain curve of saturated soft clay is made hyperbolic. During the reloading period, when the loading quantity is less than the unloading quantity, the curve is hyperbolic, and when the loading quantity is greater than unloading quantity the curve is a straight line which keeps hardening. The plastic deformation and elastic deformation of test samples produced in the test have linear relation with the unloading level. On the basis of the original constitutive relation, axial circulation loading and unloading constitutive equation have been established using the loading axial stresses, initial tangent modulus, maximum unloading axial strain and its initial secant modulus as parameters. The reliability of equations was verified as well. The analysis of various plastic hysteresis reveals that as the unloading stress level increases, the hysteresis increases too and conforms to the quadratic curve relationship. This provides a certain engineering practice value for the strength and deformation characteristics of soft soil under cyclic loading.
Highlights
With the rapid development of the economy, the construction of transportation infrastructure along the coast and along the Yangtze River has developed rapidly
The unloading curve is mainly composed of curved segments, which explains the non-linear characteristics of saturated soft soil, which is different from the rock unloading curve
In the stress-strain relationship curve of axial cyclic loading and unloading, the tangent slope corresponding to the axial force of 0 on the curve is usually taken as the initial deformation modulus of the specimen during loading or unloading
Summary
With the rapid development of the economy, the construction of transportation infrastructure along the coast and along the Yangtze River has developed rapidly. Airports, highways and railway projects, bridge and tunnel projects, subways and river tunnel projects, underground shopping malls, hydropower stations, and large oil tanks have been built. These projects are often subject to variable loads. Based on the experimental results, the cyclic loading and unloading constitutive equation was established [2, 5, 6]; and the plastic hysteresis energy was calculated and fitted It provides a theoretical basis for deformation prediction of saturated clay foundation, and provides guidance for practical application of engineering
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