Field Test Method for Determination of Strength Properties of Unsaturated Soils

Abstract

The invention relates to a field test and measurement method of strength characteristics of unsaturated soil, which comprises: digging a test hole A and a suction test hole B with a Luoyang shovel, setting a measuring device of strength characteristics of unsaturated soil above the test hole A, setting a tensiometer at the bottom of the suction test hole B, carrying out loading test in the test hole A, observing changes in the reading of the tensiometer in the suction test hole B, drawing a load-settlement curve, and carrying out other steps. Field test and measurement from the Luoyang shovel-formed holes to strength characteristics of unsaturated soil are achieved herein; the field test and measurement method and device to acquire strength characteristics of unsaturated soil through the loading test and the tensiometer measurement test are provided; the load-settlement curve under different suction levels is drawn through groups of unsaturated soil loading tests under different suction levels so that strength characteristic parameters of unsaturated soil are attained; therefore, strength of the unsaturated soil under any suction level is calculated.

Description

technical field [0001] The invention relates to a method for measuring the bearing properties of soil layers, in particular to a field test method for measuring the strength properties of unsaturated soil. Background technique [0002] Suction is the basis and core of the theoretical system of unsaturated soil mechanics, and it is the fundamental difference between unsaturated soil and saturated soil. Suction is of great significance in explaining the mechanical properties of unsaturated soil in geotechnical engineering problems. The design and construction of unsaturated foundations is guided by the control of settlement and deformation. Changes in the suction of unsaturated soils will cause uneven settlement or excessive settlement of the foundation, which has an important impact on the deformation and strength of unsaturated soils. The suction of unsaturated soil can be measured indoors and on site. It is mainly divided into matrix suction and seepage suction. According t...

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Problems solved by technology

[0003] The indoor test of the mechanical properties of unsaturated soil and the constitutive relationship of unsaturated soil adopts borehole sampling to carry out the test indoors, but the borehole sampling will cause disturbance to the unsaturated soil, and the produced sample will cause cracks to cause suction fluctuations and damage its inherent structural properties

Self-drilling techniques using flushing or compressed air are not suitable for unsaturated soil conditions because it causes changes in pore water pressure or pore air pressure, affecting the suction of the soil layer at the bottom of the hole (pore water pressure or pore air pressure)

Chinese Journal of Geotechnical Engineering (2006, Vol. 28, No. 2) "Study on the relationship between suction and strength in the dry-wet cycle process" article studied the effect of the dry-wet cycle process on the strength of unsaturated soils caused by changes in the water environment. However, the dry-wet cycle test is carried out under no load, which is inconsistent with the actual formation with a certain buried depth.

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