岩土力学
巖土力學
암토역학
ROCK AND SOIL MECHANICS
2013年
8期
2249-2254
,共6页
粗粒土%大三轴%相对密度%剪胀性
粗粒土%大三軸%相對密度%剪脹性
조립토%대삼축%상대밀도%전창성
coarse-grained soils%large-scale triaxial test%relative density%dilatancy
采用大三轴剪切仪对3种不同相对密度的双江口心墙坝覆盖层料进行固结排水剪切试验，重点研究粗粒土的剪胀特性，分析粗粒土的剪胀性与围压、相对密度之间的关系，并检验修正剑桥模型的剪胀方程、Rowe 剪胀方程对粗粒土的适用性。结果表明，粗粒土在低围压下表现出明显的剪胀趋势，随着围压的增加，逐渐由剪胀向剪缩过渡；随着密度的增大，粗粒土的剪胀性明显增强；相变应力比是粗粒土剪胀强弱的一个重要影响因素，其随密度的增加而增加，随围压的增大则呈线性减小趋势；粗粒土的剪胀性与相对密度、围压关系密切，根据试验数据得出最大剪胀率 fd 与相对密度 rD 、围压3s之间的关系式；修正剑桥模型的剪胀方程不能反映粗粒土的剪胀性；Rowe 剪胀方程在一定程度上能反映粗粒土的剪胀性，但高围压下在压缩阶段低估了其压缩性，而在剪胀阶段则高估了其剪胀性。
採用大三軸剪切儀對3種不同相對密度的雙江口心牆壩覆蓋層料進行固結排水剪切試驗，重點研究粗粒土的剪脹特性，分析粗粒土的剪脹性與圍壓、相對密度之間的關繫，併檢驗脩正劍橋模型的剪脹方程、Rowe 剪脹方程對粗粒土的適用性。結果錶明，粗粒土在低圍壓下錶現齣明顯的剪脹趨勢，隨著圍壓的增加，逐漸由剪脹嚮剪縮過渡；隨著密度的增大，粗粒土的剪脹性明顯增彊；相變應力比是粗粒土剪脹彊弱的一箇重要影響因素，其隨密度的增加而增加，隨圍壓的增大則呈線性減小趨勢；粗粒土的剪脹性與相對密度、圍壓關繫密切，根據試驗數據得齣最大剪脹率 fd 與相對密度 rD 、圍壓3s之間的關繫式；脩正劍橋模型的剪脹方程不能反映粗粒土的剪脹性；Rowe 剪脹方程在一定程度上能反映粗粒土的剪脹性，但高圍壓下在壓縮階段低估瞭其壓縮性，而在剪脹階段則高估瞭其剪脹性。
채용대삼축전절의대3충불동상대밀도적쌍강구심장패복개층료진행고결배수전절시험，중점연구조립토적전창특성，분석조립토적전창성여위압、상대밀도지간적관계，병검험수정검교모형적전창방정、Rowe 전창방정대조립토적괄용성。결과표명，조립토재저위압하표현출명현적전창추세，수착위압적증가，축점유전창향전축과도；수착밀도적증대，조립토적전창성명현증강；상변응력비시조립토전창강약적일개중요영향인소，기수밀도적증가이증가，수위압적증대칙정선성감소추세；조립토적전창성여상대밀도、위압관계밀절，근거시험수거득출최대전창솔 fd 여상대밀도 rD 、위압3s지간적관계식；수정검교모형적전창방정불능반영조립토적전창성；Rowe 전창방정재일정정도상능반영조립토적전창성，단고위압하재압축계단저고료기압축성，이재전창계단칙고고료기전창성。
Using large-scale shearing device, isotropic consolidated-drained triaxial tests under different confining pressures are performed for three relative densities overburden material of Shuangjiangkou earth dam. The dilatancy of coarse-grained materials is investigated; the relationship among dilatancy, relative density and confining pressure are discussed; and applicability of dilatancy equation of modified Cam-clay model and Rowe dilatancy equation for coarse-grained soils are tested. It is found that the confining pressure and initial density influence dilatancy evidently; that is, under low confining pressure coarse-grained soils are characterized by volumetric dilatancy; and with the increasing of confining pressure they exhibit volumetric compression. The increasing of density results in the increase of dilatancy. Phase transformation stress ratio is an important factor affecting dilatancy, which exhibit increasing with the increase of density and linear decrease with the increase of confining pressure. According to the test data, a relationship formula among dilatancy ratio and relative density and confining pressure is obtained. Dilatancy equation of modified Cam-clay model cannot reflect the dilatancy; and Rowe dilatancy equation can reflect the dilatancy of the coarse-grained materials;but when confining pressure is higher it underestimate the compression during compression stage and overestimate the dilatancy during shearing stage.
