曹妃甸填海造陸區(qū)吹填土P-N固化試驗(yàn)與機(jī)理分析
發(fā)布時(shí)間：2018-09-05 10:59
【摘要】：填海造陸已成為緩解沿海地區(qū)土地資源緊張的有效途徑,而吹填土造陸是填海造陸的主要方式。由于吹填土具有容重小、孔隙比大、含水量高、強(qiáng)度極低等特點(diǎn),不能直接作為地基土使用,因此,采用化學(xué)固化劑對(duì)吹填土進(jìn)行加固處理,以期提高吹填土強(qiáng)度,對(duì)填海造陸工程場地地基土處理具有重要的實(shí)踐意義。本文以河北省唐山市曹妃甸填海造陸區(qū)吹填土為研究對(duì)象,以聚丙烯酰胺(PAM)和水玻璃(Na2Si O3)為固化劑,設(shè)計(jì)P-N(PAM和水玻璃)固化方案。在顆粒分析、擊實(shí)試驗(yàn)、易溶鹽分析、地下水分析、XRF成分分析等測試得到吹填土理化性質(zhì)的基礎(chǔ)上,通過無側(cè)限抗壓強(qiáng)度試驗(yàn)、三軸剪切試驗(yàn)等,對(duì)固化前后吹填土的變形和強(qiáng)度進(jìn)行了對(duì)比分析,結(jié)合正交試驗(yàn),分析了PAM和水玻璃摻入比例、養(yǎng)護(hù)齡期等因素對(duì)固化效果的影響程度,確定了最優(yōu)固化方案。借助模糊評(píng)價(jià)法,對(duì)PAM和水玻璃單摻、雙摻的固化效果進(jìn)行了綜合評(píng)價(jià)。對(duì)比研究了固化前后吹填土微觀結(jié)構(gòu)變化,并揭示了吹填土固化機(jī)理。研究表明:(1)曹妃甸填海造陸區(qū)吹填土為粉土,易溶鹽以堿金屬氯鹽和硫酸鹽為主,地下水水質(zhì)偏堿性,其主要礦物成分為黏土礦物,屬于堿性土。(2)單摻PAM固化吹填土的無側(cè)限抗壓強(qiáng)度、抗剪強(qiáng)度指標(biāo)C、Φ均與PAM摻入比例和養(yǎng)護(hù)齡期呈正相關(guān),隨著PAM摻入比例和養(yǎng)護(hù)齡期的增加,三軸應(yīng)力應(yīng)變曲線從應(yīng)變硬化型逐漸轉(zhuǎn)化為應(yīng)變軟化型。(3)單摻水玻璃固化吹填土的無側(cè)限抗壓強(qiáng)度、抗剪強(qiáng)度指標(biāo)C、Φ均與水玻璃摻入比例和養(yǎng)護(hù)齡期呈正相關(guān),隨著水玻璃摻入比例和養(yǎng)護(hù)齡期的增加,三軸應(yīng)力應(yīng)變曲線應(yīng)變軟化趨勢不斷增強(qiáng),固化吹填土抗變形能力及強(qiáng)度均得到提高。(4)隨著養(yǎng)護(hù)齡期的增長,P-N(PAM和水玻璃)雙摻固化吹填土的無側(cè)限抗壓強(qiáng)度及C、Φ提高幅度越大,三軸應(yīng)力應(yīng)變曲線為應(yīng)變軟化型,抗剪強(qiáng)度和抗變形能力均得到提高。(5)根據(jù)模糊評(píng)價(jià)法對(duì)吹填土固化效果進(jìn)行了綜合評(píng)價(jià),P-N(PAM和水玻璃)雙摻好于單摻,單摻水玻璃好于單摻PAM。(6)養(yǎng)護(hù)齡期、固化劑摻入比例等對(duì)吹填土的固化效果影響程度由大到小分別為養(yǎng)護(hù)齡期水玻璃摻入比例PAM摻入比例;最優(yōu)固化方案為PAM、水玻璃摻入比例分別為0.3%、4%、養(yǎng)護(hù)齡期28天。(7)固化前吹填土微觀結(jié)構(gòu)表現(xiàn)為松散、孔隙發(fā)育、孔徑分布以超大孔和大孔為主,固化后吹填土微觀結(jié)構(gòu)表現(xiàn)為孔隙比和孔隙度減小、孔徑則轉(zhuǎn)變?yōu)橐灾锌准靶】诪橹�、分維增大。養(yǎng)護(hù)齡期越長,固化吹填土的孔隙越少,孔徑越小,分維越大。(8)PAM固化機(jī)理主要為絮凝作用、吸附作用及屏蔽作用,在顆粒間連接架橋形成網(wǎng)絡(luò)結(jié)構(gòu),加強(qiáng)了吹填土顆粒膠結(jié)作用;水玻璃固化機(jī)理為黏土礦物與水玻璃間發(fā)生化學(xué)反應(yīng)生成硅酸凝膠和硅酸鈣凝膠顆粒,填充孔隙;P-N(PAM和水玻璃)固化的機(jī)理為PAM加強(qiáng)吹填土顆粒間凝聚力的同時(shí),水玻璃能夠與吹填土反應(yīng)生成凝膠和沉淀填充孔隙。
[Abstract]:Reclamation has become an effective way to alleviate the shortage of land resources in coastal areas, and reclamation with dredged fill is the main way to reclaim land from the sea.Because dredged fill has the characteristics of small bulk density, large void ratio, high water content and very low strength, it can not be used as foundation soil directly. It is of great practical significance to improve the strength of dredged fill soil for the foundation soil treatment of reclamation and land-building engineering site.In this paper, the dredged fill soil in Caofeidian reclamation and land-building area of Tangshan City, Hebei Province, was taken as the research object, and the P-N (PAM) and water glass (Na2Si O3) solidification schemes were designed with polyacrylamide (PAM) and sodium silicate (Na2Si O3) as solidifying agents. Based on the analysis of soluble salt, groundwater and XRF components, the physical and chemical properties of dredger fill are obtained. The deformation and strength of dredger fill before and after solidification are compared and analyzed by unconfined compressive strength test and triaxial shear test. Combined with orthogonal test, the factors such as the proportion of PAM and sodium silicate, curing age and so on are analyzed. The optimum solidification scheme was determined. The solidification effect of PAM and sodium silicate mixed with single and double was evaluated by fuzzy evaluation method. The microstructure changes of dredger fill before and after solidification were studied and the solidification mechanism of dredger fill was revealed. The salt is mainly alkali chloride and sulfate, the groundwater quality is alkaline, and the main mineral is clay mineral, which belongs to alkaline soil. (2) The unconfined compressive strength, shear strength index C, _are positively correlated with PAM mixing ratio and curing age, with the increase of PAM mixing ratio and curing age, triaxial stress. (3) The unconfined compressive strength, shear strength index C and_of the dredger fill solidified with sodium silicate are positively correlated with the proportion of sodium silicate and curing age, and the trend of strain softening of the triaxial stress-strain curve increases with the increase of the proportion of sodium silicate and curing age. (4) With the increase of curing age, the unconfined compressive strength and C, _of P-N (PAM) and water glass mixed solidified dredger fill are increased, and the triaxial stress-strain curve is strain-softening type, and the shear strength and deformation resistance are improved. (5) According to the fuzzy evaluation method. The consolidation effect of dredger fill is evaluated comprehensively. P-N (PAM) and sodium silicate are better than single-doped, and single-doped sodium silicate is better than single-doped PAM. (6) The influence degree of curing age and the proportion of solidifying agent on the consolidation effect of dredger fill from large to small are respectively the proportion of sodium silicate in curing age; the optimum curing scheme is PAM and sodium silicate in curing age. (7) Before solidification, the microstructure of dredged fill is loosened, pore development, pore size distribution is dominated by super-large pores and macropores, and after solidification, the microstructure of dredged fill is characterized by porosity ratio and porosity reduction, pore size is mainly changed to mesopore and small pores, fractal dimension is increased. (8) PAM solidification mechanism is mainly flocculation, adsorption and shielding, bridging between particles to form a network structure, which strengthens the cementation of dredged fill particles; water glass solidification mechanism is the chemical reaction between clay minerals and sodium silicate to form silicate gel and calcium silicate coagulation. The solidification mechanism of P-N (PAM and sodium silicate) is that PAM can enhance the cohesion between particles of dredged fill, and water glass can react with dredged fill to form gel and precipitate to fill the pores.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P756.8;TU41
本文編號(hào)：2224067
[Abstract]:Reclamation has become an effective way to alleviate the shortage of land resources in coastal areas, and reclamation with dredged fill is the main way to reclaim land from the sea.Because dredged fill has the characteristics of small bulk density, large void ratio, high water content and very low strength, it can not be used as foundation soil directly. It is of great practical significance to improve the strength of dredged fill soil for the foundation soil treatment of reclamation and land-building engineering site.In this paper, the dredged fill soil in Caofeidian reclamation and land-building area of Tangshan City, Hebei Province, was taken as the research object, and the P-N (PAM) and water glass (Na2Si O3) solidification schemes were designed with polyacrylamide (PAM) and sodium silicate (Na2Si O3) as solidifying agents. Based on the analysis of soluble salt, groundwater and XRF components, the physical and chemical properties of dredger fill are obtained. The deformation and strength of dredger fill before and after solidification are compared and analyzed by unconfined compressive strength test and triaxial shear test. Combined with orthogonal test, the factors such as the proportion of PAM and sodium silicate, curing age and so on are analyzed. The optimum solidification scheme was determined. The solidification effect of PAM and sodium silicate mixed with single and double was evaluated by fuzzy evaluation method. The microstructure changes of dredger fill before and after solidification were studied and the solidification mechanism of dredger fill was revealed. The salt is mainly alkali chloride and sulfate, the groundwater quality is alkaline, and the main mineral is clay mineral, which belongs to alkaline soil. (2) The unconfined compressive strength, shear strength index C, _are positively correlated with PAM mixing ratio and curing age, with the increase of PAM mixing ratio and curing age, triaxial stress. (3) The unconfined compressive strength, shear strength index C and_of the dredger fill solidified with sodium silicate are positively correlated with the proportion of sodium silicate and curing age, and the trend of strain softening of the triaxial stress-strain curve increases with the increase of the proportion of sodium silicate and curing age. (4) With the increase of curing age, the unconfined compressive strength and C, _of P-N (PAM) and water glass mixed solidified dredger fill are increased, and the triaxial stress-strain curve is strain-softening type, and the shear strength and deformation resistance are improved. (5) According to the fuzzy evaluation method. The consolidation effect of dredger fill is evaluated comprehensively. P-N (PAM) and sodium silicate are better than single-doped, and single-doped sodium silicate is better than single-doped PAM. (6) The influence degree of curing age and the proportion of solidifying agent on the consolidation effect of dredger fill from large to small are respectively the proportion of sodium silicate in curing age; the optimum curing scheme is PAM and sodium silicate in curing age. (7) Before solidification, the microstructure of dredged fill is loosened, pore development, pore size distribution is dominated by super-large pores and macropores, and after solidification, the microstructure of dredged fill is characterized by porosity ratio and porosity reduction, pore size is mainly changed to mesopore and small pores, fractal dimension is increased. (8) PAM solidification mechanism is mainly flocculation, adsorption and shielding, bridging between particles to form a network structure, which strengthens the cementation of dredged fill particles; water glass solidification mechanism is the chemical reaction between clay minerals and sodium silicate to form silicate gel and calcium silicate coagulation. The solidification mechanism of P-N (PAM and sodium silicate) is that PAM can enhance the cohesion between particles of dredged fill, and water glass can react with dredged fill to form gel and precipitate to fill the pores.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P756.8;TU41
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