A Method for Discriminating Seismic Liquefaction of Deeply Buried Saturated Sand

Abstract

The invention provides a deep saturated sand earthquake-induced liquefaction judgment method, which comprises six steps: 1) determining standard penetration numbers of a deep saturated sand layer at different positions and in different depths; 2) determining seismic cyclic shear stress ratio CSR of different standard penetration test points of the deep saturated sand layer; 3) determining actual critical overlying effective stress of standard penetration test through a hypothetical test method; 4) obtaining normalized standard penetration numbers of the different standard penetration test points at different positions and in different depths; 5) determining liquefaction-resistance cyclic shear stress ratio CRR7.5; and 6) making a comparison between the seismic cyclic shear stress ratio CSR and the liquefaction-resistance cyclic shear stress ratio CRR7.5, and carrying out earthquake-induced liquefaction judgment. The method can overcome the defect that a standard penetration number liquefaction judgment method in the current specifications cannot be applied to the soil layer, the depth of which is larger than 20m, and can enable the existing standard penetration number liquefaction judgment method to be expanded and applied to deep saturated sand earthquake-induced liquefaction judgment.

Description

technical field [0001] The invention belongs to the field of geotechnical anti-seismic safety evaluation, and relates to a method for distinguishing earthquake liquefaction of deeply buried saturated sand. Background technique [0002] More than 80% of my country's hydropower resources are distributed in the western region with frequent and strong seismic activities. Most of the river beds in this area have deep overburden layers, and there are often soil layers or lenses that may be liquefied under earthquakes such as sandy soil in the deep overburden layers. With the implementation of the western development strategy, more and more earth-rock dam projects will be built on deep overburden layers. The stability of sandy soil or its lenses under earthquake action in deep overburden layers is related to engineering safety and feasibility. However, the identification of seismic liquefaction of deeply buried saturated sand is a difficult problem in both academic and engineering ...

AI Technical Summary

Problems solved by technology

The standard penetration test is a widely used on-site in-situ test method. The method of judging the possibility of foundation soil liquefaction based on the standard penetration test is widely used in engineering, but the standard penetration test liquefaction judgment method in the existing codes is applicable The depth of the foundation soil is within 20m (the overlying effective stress is roughly 200kPa), and the existing method is not applicable to the seismic liquefaction judgment of deeply buried saturated sandy soil exceeding 20m (the overlying effective stress is roughly 200kPa).

Images