本文選題：土石壩 + 心墻�。� 參考：《大連理工大學(xué)》2014年碩士論文

【摘要】：土石壩具有投資省、施工快以及對(duì)地質(zhì)條件的適應(yīng)范圍廣等優(yōu)點(diǎn),是國(guó)內(nèi)外重點(diǎn)發(fā)展的壩型之一。近年來(lái),土石壩的高度有了很大發(fā)展,正在實(shí)現(xiàn)150m級(jí)向300m級(jí)高壩的跨越。如雙江口(312m)、兩河口(293m)、糯扎渡(261.5m)等等。 高土石壩多采用摻礫黏土料作防滲心墻。這種人工摻礫土料的級(jí)配寬,有相當(dāng)?shù)酿ち：?小顆粒充分填充大顆粒孔隙,可獲得很高的干密度,因而具有良好的防滲性,同時(shí)粗顆粒能夠形成骨架,抗剪強(qiáng)度和彈性模量均較高,應(yīng)用于高土石壩作心墻料,既起防滲作用,又與兩側(cè)壩殼料的強(qiáng)度變形特性相差不大,較好地承擔(dān)荷載,改善心墻的應(yīng)力狀態(tài),減少發(fā)生水力劈裂的可能性。 高土石壩的壩殼料一般有向外變形的趨勢(shì),這會(huì)引起心墻應(yīng)力減小,一旦發(fā)生地震心墻頂部容易出現(xiàn)動(dòng)強(qiáng)度不足的問(wèn)題,甚至產(chǎn)生裂縫,若繼續(xù)加震將導(dǎo)致大壩頂部壩坡失穩(wěn)等。心墻土料摻礫可以提高其地震動(dòng)強(qiáng)度,但摻礫后心墻與壩殼剛度差別變小,在地震引起剪應(yīng)力的分擔(dān)上,摻礫土料心墻分擔(dān)的比例比黏土心墻大。因此摻礫心墻的動(dòng)強(qiáng)度能否滿足要求需要進(jìn)一步研究。 本文采用GDS三軸儀進(jìn)行了一系列飽和摻礫土料的靜力和動(dòng)力試驗(yàn),研究了心墻頂部的摻礫土料在低圍壓下的動(dòng)強(qiáng)度特性。本文的主要工作如下： (1)進(jìn)行了靜力三軸固結(jié)不排水試驗(yàn),得到了摻礫料的應(yīng)力—應(yīng)變、孔壓、有效應(yīng)力路徑曲線,求得其靜強(qiáng)度指標(biāo)。 (2)進(jìn)行了動(dòng)力三軸試驗(yàn),研究了摻礫土料的動(dòng)力特性,得到了摻礫土料的動(dòng)模量和阻尼比曲線及參數(shù)。 (3)進(jìn)行了動(dòng)強(qiáng)度試驗(yàn),得到如下規(guī)律：①相同圍壓作用下試樣的動(dòng)強(qiáng)度一般隨固結(jié)應(yīng)力比先增大后減小。②試樣的摻礫比例增大可以提高其動(dòng)強(qiáng)度,且隨著圍壓的增大動(dòng)強(qiáng)度提高愈顯著。動(dòng)摩擦角φd隨摻礫比例提高而變大,但動(dòng)粘聚力cd隨摻礫比例提高而變小。摻礫比例變化引起其動(dòng)力指標(biāo)的變化與靜力情況下的變化相似。③試樣的動(dòng)應(yīng)變隨振次N的變化與rc的大小有關(guān),rc為動(dòng)應(yīng)力和土樣的固結(jié)不排水強(qiáng)度之比。動(dòng)應(yīng)變隨振次的變化曲線存在一個(gè)轉(zhuǎn)折點(diǎn),在轉(zhuǎn)折點(diǎn)出現(xiàn)以前,應(yīng)變隨振次變化緩慢；轉(zhuǎn)折點(diǎn)出現(xiàn)以后應(yīng)變急劇增長(zhǎng)。④通過(guò)3組不同固結(jié)比動(dòng)強(qiáng)度試驗(yàn),繪制出地震總應(yīng)力抗剪強(qiáng)度線并求得地震總應(yīng)力強(qiáng)度參數(shù)。
[Abstract]:Earth-rock dam is one of the most important dam types at home and abroad because of its advantages of low investment, fast construction and wide adaptability to geological conditions.In recent years, the height of earth-rock dam has been greatly developed, and the span from 150m to 300m is being realized.Such as Shuangjiang Estuary (312m), Liangkou (293m), Nuozhadu (261.5m) and so on.High earth-rockfill dams often use gravel clay as anti-seepage core wall.The gradation of the artificial gravel soil is wide, and the content of clay is considerable. The small particles can fill the pores of large particles to obtain a very high dry density, so it has good impermeability, and the coarse particles can form a skeleton.The shear strength and elastic modulus are both high. When used as core wall material of high earth-rock dam, it not only acts as an anti-seepage effect, but also has little difference with the strength and deformation characteristics of both sides of dam shell, so it can bear the load better and improve the stress state of the core wall.Reduce the possibility of hydraulic fracturing.Generally speaking, the shell material of high earth rockfill dam tends to deform outward, which will cause the stress of the core wall to decrease, and once the earthquake occurs, the problem of insufficient dynamic strength on the top of the core wall is likely to occur, and even cracks will occur.If the earthquake continues, it will lead to the instability of the dam slope at the top of the dam.The strength of ground motion can be increased by adding gravel to core wall, but the difference between the stiffness of core wall and dam shell becomes smaller after adding gravel, and the proportion of core wall with gravel is larger than that of clay core wall in shear stress sharing caused by earthquake.Therefore, whether the dynamic strength of gravel core wall can meet the requirements needs further study.In this paper, a series of static and dynamic tests of saturated gravel admixture are carried out with GDS triaxial instrument. The dynamic strength of gravel admixture at the top of core wall under low confining pressure is studied.The main work of this paper is as follows:1) the static triaxial consolidation undrained test was carried out, and the stress-strain, pore pressure and effective stress path curves of gravel admixture were obtained, and the static strength index was obtained.(2) dynamic triaxial test was carried out, and the dynamic characteristics of gravel soil were studied, and the dynamic modulus and damping ratio curves and parameters were obtained.(3) the dynamic strength tests have been carried out. The results show that the dynamic strength of the specimen under the same confining pressure is generally increased with the increase of the consolidation stress ratio first and then decreased by the increase of the proportion of gravel admixture of the sample. The dynamic strength of the specimen can be increased by increasing the ratio of gravel to gravel.With the increase of confining pressure, the dynamic strength increases more significantly.The dynamic friction angle 蠁 d increases with the increase of boulder ratio, but the dynamic cohesive force CD decreases with the increase of gravel ratio.The change of dynamic index caused by the ratio of mixed gravel is similar to that under static condition. The dynamic strain of specimen changes with the vibration degree N and the magnitude of RC is related to the ratio of dynamic stress to consolidation undrained strength of soil sample.There is a turning point in the curve of dynamic strain with vibration times. Before the turning point appears, the strain changes slowly with vibration times, and the strain increases sharply after turning point.The shear strength line of seismic total stress is drawn and the parameters of seismic total stress intensity are obtained.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TV641;TV41

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