土工材料浸水特性的试验研究

【作者】 黄尚锦；

【导师】 李同录；

【作者基本信息】 长安大学 ， 地质工程， 2005， 硕士

【摘要】 近年来,高等级公路路基因地下水入浸发生大范围湿陷;在建筑工程中,由于地基浸水而导致其局部下沉,造成差异沉降,出现楼体倾斜、墙壁裂缝等病害。因此,对各种土工材料的黄土地基浸水后物理力学指标变化进行研究具有理论和实践意义。 本文选用了素土、不同配比的加砂黄土和不同配比不同龄期的粉煤灰土、灰土、水泥黄土等土工材料,通过击实试验获取了最优含水量。再在最优含水量下制备了击实试样,对每种击实土分别做浸水和不浸水条件下的室内直剪试验、无侧限抗压试验、压缩试验和湿陷试验,通过对大量试验结果的对比分析,获得了以下认识: 1.各种土工材料在击实后均不具有湿陷性,因此各类工程中发生的地基沉陷是由土体强度因浸水而急剧衰减引起的;但也不排除压实度不够的因素。 2.在黄土中掺入砂能提高土体的抗剪强度、抗压强度和压缩模量,根据试验结果采用1:9的加砂量比较适合。 3.粉煤灰土有较高的强度,但对水的敏感性高,水稳性差,饱水后强度急剧降低。 4.灰土的试验结果表明,体积比为1:9的灰土强度比3:7、2:8的高,但2:8的水稳性最好,而目前工程应用最为广泛的3:7灰土含灰量偏大,对水的敏感性较大。 5.水泥黄土是一种比较理想的固化材料,能在较短时间内达到较高的强度,而且达到的强度和软化系数较其它的高。 6.在黄土中加入浆糊状的熟糯米浆,在土体含水量为14%时抗压强度可达到0.41MPa,且抗压强度随含水量的减小呈幂函数增加。 在本次试验中,灰土、水泥黄土在初期浸水后的抗剪强度、抗压强度并不马上降低,但相对同龄期没浸水的是降低的,在本文中引入相对软化系数和软化速率,能真实的反映出有化学反映参与加固黄土的土工材料对水的敏感性。 糯米土作为一种环保型的土工材料,本文做了一定的反映其物理力学指标的试验,为环保型材料的选取提供参考。 通过实验得出的各种土工材料的物理力学指标和浸水前后强度变化为地基的选材、设计提供了依据。更多还原

【Abstract】 In recent years, the infiltration of water resulted settlement in a lot of foundations o highway. The problem also presented in building foundations, which caused building inclinin and cracked. So it is significant theoretically and practically to research the variation of so properties while the foundation soaks by underground water.In the research work, amount of tests of the soil engineering materials such as sand-loess, different mixture ratio and different age fly ash, lime-loess and loess-cement has been done. Optimum moisture content is acquired by compaction test, and the materials of test are made in optimum moisture content. In saturated and un-saturated conditions, each soil sample is made shear strength test, unconfined compression test, compression test and collapsible test. The test results are analyzed and got the knowledge as follow:1. After compaction, all sorts of materials don’t have collapsible, the settlement of foundations in the constructions may resulted from sharp decline of loess strength because of infiltration of water. But the degree of compaction which is not enough is may the factor of settlement.2. Sand mixed with loess can improve the compressive strength; shear strength and modulus of compressibility of loess. And according to experimental results, the proportion of sand-loess as 1:9 is better.3. Fly ash possesses higher strength, but it sensitive to water, so its strength water-stability is slow and after infiltration its strength decline quickly.4. The result of the lime-loess test: The strength of 1:9 lime-loess compare with 2:8 and 3:7 is higher, but the water-stabilizing property of 2:8 is the best. Moreover the lime-loess of 3:7 that usually uses on engineering contains more lime, rightness waters compare greatly.5. The loess-cement is a kind of more ideal solid material. It can attain higher strength in a short time. Moreover it’ s strength and softening coefficient are higher than others.6.The boiled flour of polished glutinous rice for a while and add it into loess, when it’s moisture content attains to 14%, its compressive strength can attain to 0.41MPa, and the strength changes sharply with the moisture content.In this test, fly ash and loess-cement’s shear strength and compression strength didn’t reduce at once when drop them into water, but their strength reduced compared with what at the same age and without soaked with water. In this thesis, we introduce relative softening coefficient and softening rate, which can reflect the material’s sensitivity to water.Polished glutinous rice loess is an environmental benefit soil engineering materials. We have done a certain amount of experiment that can reflect the physics and mechanics index of polished glutinous rice loess in order to offer one to consult for the choice of environmental material.By doing this experiments, we have gained the physics and mechanics index and change of strength around being soaked with water of all kinds of materials, these results can offer warranty for designing and selecting suitable soil engineering materials.更多还原