Study On Test Of Shear Strength Indices Of Tianjin Shallow Soil

The development of New coastal Area in Tianjin has been bracketed the nation total development strategy, It will be make Geotechnical engineering developed. In the course of exploration, the correct application of strength indices under different conditions is an important and hard job. But many engineers make a lot of mistakes in the testing conditions. It is well known that the strength indices under different conditions is different . To determine correctly strength parameters by laboratory test calls for experience with engineering application .Base on this, The variation of strength indices of Tianjin shallow soils has been studied .In this paper, It was obtained that the Quaternary subdivision and sequence formation of Tianjin region and statistical chart of the physical norm for each soil lever, at the same time, The at-rest lateral earthpressure coefficient- K₀ was studied for shallow soils. Through comprising K₀ -values under different conditions, It is obtained that the distribution patterns for K₀ -values and the statisticschart of the physical norm and K₀ -coefficient. It is reviewed that The Mohr-Coulomb FailureTheory, stress path and the standard of soils damaged in tri-axial shear test played very important roles in studying strength parameters. It is obtained that the shear feature of normal consolidated cohesive soil and cohesion less soil .The Unconsolidated-Undrained (UU) shear strength indices was studied .It was determined by kinds of influence factors during the testing under different conditions. The Consolidated-Undrained (CU) shear strength indices were studied in two facets. The first, the original stress state of soil samples is resumed by two pro-consolidation treatment methods, It is shown that the strength parameters under balanced pressure condition is higher than K₀ pressure condition. On the other hand, the relationship between CU-shear strengthindices and consolidated stress is even more complicated, the increase in consolidated stress causes an increase in strength indices. Before beginning CU-tri axial testing, the samples should be consolidate in 1.5 times soil level self-weight pressure and it will reduce the influence of sampling disturbing on soil engineering properties. In the end, this paper shows how to use the shear strength indices in geotechnical engineering.