Lateral Swelling Pressure of Expansive Soil and Its Effect on Gravity Retaining Wall
(2.School of Traffic and Transport Engineering, Changsha University of Science & Technology , Changsha, Hunan, China 410114)
【Abstract】In order to investigate lateral swelling pressure (LSP) of expansive soil under the various vertical load and its effect on gravity retaining wall stability, the test apparatus and method for measuring LSP were designed based on the conventional oedometer. The variation law of LSP of expansive soil from Guangxi Baise with different vertical loads was obtained. A numerical simulation for the development of moisture content was carried out on an expansive soil embankment, under a long-term effect of specific wet and hot climate condition. Combined with the results of laboratory LSP tests, variations of LSP along the back of wall at rest with the depth and time were analyzed. According to the relationship between LSP and lateral swelling ratio obtained by laboratory tests, the variation of LSP with lateral swelling of expansive soil on back of wall was analyzed. Besides, the impact on the stability against sliding and over-turning of retaining wall was also discussed. The results show that the expansive soil can still produce come LSP after the immersion under the lateral confining and zero upper load condition. The LSP increases significantly with the increase in vertical load ranging from 0 to 50 kPa, and is greater than the corresponding vertical load. When the value of vertical load is greater than 100 kPa, LSP increases very small and remains stable. When the vertical load increases to the vertical swelling pressure of the specimen in the constant volume condition, the LSP reaches to the maximum. Under the long-term effect of hot and wet climate, soil moisture content and lateral swelling pressure along the back of retaining wall gradually increases, and the action point of the force moves down gradually. After five years, the variation of moisture content becomes stable, and the distribution of LSP along the back of retaining wall is the parabola. The lateral swelling pressure can increase to three times of earth pressure at rest, and its action point locates in the middle of the wall. The retaining wall will horizontally move in 2.0 cm under the effect of LSP. The LSP can be extremely reduced, and the stability coefficient against sliding and overturning of the wall will meet the requirement of specifications if a lateral swelling of 2.6 cm of expansive soil is allowable behind the wall.
【Keywords】 road engineering ; gravity retaining wall ; experimental research ; expansive soil ; lateral swelling pressure ;
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