High-pressure compressibility and shear strength data for soils

Abstract

Soil behaviour is often an important consideration in the design of protective systems for blast and impact threats, as the properties of a soil can greatly affect the impulse generated from buried explosive devices, or the ability of a soil-filled structure to resist ballistic threats. Numerical modelling of these events often relies on extrapolation from low-pressure experiments. To develop soil models that remain accurate at very high pressures there is a need for data on soil behaviour under these extreme conditions. This paper demonstrates the use of a high-pressure multi-axial test apparatus to provide compressibility and shear strength data for four dry sandy soils. One-dimensional compression experiments were performed to axial stresses of 800 MPa, where the effects of particle-size distribution were observed with respect to compressibility and bulk unloading modulus. Each soil followed a bilinear normal compression line (NCL): more uniform soils initially had higher compression indices, but all four NCLs began to converge at void ratios below e ≈ 0.3. The failure surface of a sand was characterized to mean effective stress [Formula: see text] > 400 MPa using reduced triaxial compression experiments, removing the need to rely on extrapolation from low-pressure data.

Predicting Crater Formation from Failure of Pressurized Water Mains through Analogy with Buried Explosive Events

“…Above ground level the air was initialised at atmospheric pressure (101 kPa), air in the pipe was pressurised to match the water with pressure P . The soil around the pipe was modelled using the equation of state and shear data for a well-characterised sand from high pressure quasi-static experiments (Barr et al, 2018(Barr et al, , 2019. Strain rate effects were not explicitly modelled, as strain rate was shown to have no influence on the stiffness of this sand between quasi-static and high strain rates, and research on shear in soils at high strain strain rates is still ongoing (Barr et al, 2016).…”