本文選題：生物巖土工程 + 黃土�。� 參考：《西北農(nóng)林科技大學(xué)》2015年碩士論文

【摘要】：黃土廣泛分布于我國山西、陜西、甘肅等黃土高原地區(qū),由于含有大孔隙結(jié)構(gòu)且富含碳酸鹽等成分,遇水產(chǎn)生崩解,水穩(wěn)性較差。因此,黃土地區(qū)的地基、渠道等工程通常需要進(jìn)行加固處理。本文選用木質(zhì)素類高分子化合物、水泥、蝸牛生物體等單一組分或多個(gè)組分為加固材料,以楊凌黃土和延安黃土為試驗(yàn)對象,研究分析固化材料種類、摻量與養(yǎng)護(hù)齡期等因素對土體抗壓強(qiáng)度和水穩(wěn)性的影響,并對木質(zhì)素固化黃土的抗壓強(qiáng)度、抗剪強(qiáng)度、滲透性和水穩(wěn)性等工程性質(zhì)進(jìn)行研究。最后,通過分析土體加固前后物理化學(xué)性質(zhì)、微觀結(jié)構(gòu)特征及物質(zhì)成分的變化,探討木質(zhì)素磺酸鈣加固黃土的固土機(jī)理。研究結(jié)論如下。(1)低摻量木質(zhì)素磺酸鈣能夠提高水泥土的早期強(qiáng)度,但長期強(qiáng)度逐漸降低;木質(zhì)素磺酸鈣對高摻量水泥加固土體有抑制作用,因此木質(zhì)素磺酸鈣不適合與高摻量水泥配合使用。(2)木質(zhì)素磺酸鈣與蝸牛生物體復(fù)合加固土浸水后的強(qiáng)度損失率大大降低,并且隨著養(yǎng)護(hù)時(shí)間的增長,固化土抗壓強(qiáng)度的損失率越來越低。說明木質(zhì)素磺酸鈣與蝸牛生物體的摻入降低了土體對水分的敏感性,耐水性能得到改善。(3)木質(zhì)素磺酸鈣可提高土體的抗壓強(qiáng)度,降低滲透性,因而可改善黃土的工程性能;隨著摻量的增加,固化土的抗拉強(qiáng)度、抗剪強(qiáng)度指標(biāo)先增大后減小,滲透系數(shù)呈下降趨勢。木質(zhì)素磺酸鈣適宜摻量在1.0%左右,養(yǎng)護(hù)時(shí)間至少在7d以上,含水率略低于最優(yōu)含水率,應(yīng)盡量增大固化土的密度。對于不同類型的土體,木質(zhì)素?fù)搅靠赡艽嬖诓煌淖顑?yōu)摻量。(4)通過測定土體加固前后的物理化學(xué)性質(zhì),試驗(yàn)表明木質(zhì)素磺酸鈣摻入土中后土體的堿性增強(qiáng);液限明顯降低,塑限基本不變或者相對于液限來說變化幅度較小,從而導(dǎo)致塑性指數(shù)有所降低;土中的黏粒含量增大。(5)木質(zhì)素磺酸鈣摻入黃土中,使土體的強(qiáng)度提高、水穩(wěn)性改善、滲透性降低。其作用機(jī)理主要表現(xiàn)在,一方面通過分散與聯(lián)接作用使土顆粒重新排列,另一方面具有填充孔隙的作用。另外,通過其親水基與黏土顆粒表面上金屬陽離子所形成的化學(xué)鏈作用,木質(zhì)素吸附于在黏土顆粒的表面,疏水基圍繞著黏土顆粒表面形成油性層,對黏土顆粒表面的水有一定的排擠作用,并阻止水分進(jìn)入。這幾方面的綜合作用使得土顆粒間的黏結(jié)力與分子力提高,孔隙減小,土體的整體性增強(qiáng)。
[Abstract]:Loess is widely distributed in the Loess Plateau of Shanxi, Shaanxi, Gansu and other regions of China. Because of its macroporous structure and rich carbonate composition, the loess collapses in water and its water stability is poor. Therefore, the loess area foundation, canal and so on engineering usually needs to carry on the reinforcement treatment. In this paper, lignin macromolecular compounds, cement, snail organism and other single or multiple components are selected as reinforcement materials. The Yang Ling loess and Yan'an loess are taken as experimental objects to study and analyze the kinds of solidified materials. The influence of the content and curing age of soil on the compressive strength and water stability of soil is studied. The engineering properties such as compressive strength, shear strength, permeability and water stability of lignin cured loess are studied. Finally, through analyzing the changes of physical and chemical properties, microstructure and material composition of soil before and after reinforcement, the mechanism of strengthening loess with calcium lignosulfonate is discussed. The results are as follows: (1) low content of calcium lignosulfonate can improve the early strength of cement soil, but the long-term strength decreases gradually, and calcium lignosulfonate can restrain the soil reinforced with high content of cement. Therefore, calcium lignosulfonate is not suitable to be used in combination with high content cement. (2) calcium lignosulfonate and snail biological composite reinforcement soil after immersion greatly reduce the strength loss rate, and with the increase of curing time, The loss rate of compressive strength of solidified soil is lower and lower. The results show that the incorporation of calcium lignosulfonate and snail organism reduces the water sensitivity of soil, and the water resistance is improved.) calcium lignosulfonate can increase the compressive strength and reduce the permeability of the soil, thus improving the engineering properties of loess. The tensile strength, shear strength index and permeability coefficient of the solidified soil increased firstly and then decreased with the increase of the content. The suitable amount of calcium lignosulfonate is about 1.0%, the curing time is more than 7 days, the moisture content is slightly lower than the optimal moisture content, the density of solidified soil should be increased as much as possible. For different types of soil, there may be different optimal content of lignin. 4) by measuring the physical and chemical properties of soil before and after reinforcement, the experimental results show that the alkalinity of soil is enhanced and the liquid limit is obviously reduced after the addition of calcium lignosulfonate into soil. The plastic limit is basically unchanged or the variation range is small relative to the liquid limit, which leads to the decrease of the plasticity index, and the increase of clay content in soil, the addition of calcium lignosulfonate into loess, the increase of soil strength and the improvement of water stability. Permeability is reduced. The main mechanism is that, on the one hand, soil particles are rearranged by dispersion and connection, and on the other hand, they are filled with pores. In addition, lignin is adsorbed on the surface of clay particles through the interaction of hydrophilic groups with the chemical chains formed by metal cations on the surface of clay particles, and hydrophobic groups form an oily layer around the surface of clay particles. The water on the clay particle surface can be squeezed out to some extent, and prevent the water from entering. The combination of these factors makes the adhesion and molecular force between soil particles increase, the porosity decreases, and the integrity of soil is enhanced.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU444

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 張偉鋒;劉清秉;蔡松桃;;用HEC固化劑加固黃土的試驗(yàn)研究[J];人民長江;2009年03期

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本文編號：2015413