您所在的位置:首页 > 案例成果 > 科研项目 > 正文
科研项目

离子型土壤强化剂改良三峡库区黄土坡滑坡滑带土的大尺寸原位试验(2011-2013)

作者: 来源: 日期:2017-4-25 15:05:56 人气:26 评论:0 标签:

 

项目来源:国家自然科学基金(青年项目)

 

项目简介:

1)通过开展不同浓度ISS与滑带土配比试验,得出改性前后滑带土的物理性质。发现塑性指数可以作为ISS改性滑带土的评价指标,塑性指数越低,滑带土结合水膜越薄。ISS改性滑带土的XRD试验和全量化学分析表明,ISS改性前后,滑带土中并没有新的矿物晶体产生,但是晶面间距减小;ISS改性后,滑带土的阳离子含量和种类发生较大变化。

2)对不同固结程度的滑带土进行土-水特征试验,得出ISS改性后,滑带土的压缩系数减小,且黏粒含量越高,滑带土压缩系数减小的越多,说明ISS改变了黏土的结合水膜,导致其重新排列。开展土-水特征曲线试验,得出在同一终止固结压力条件下,ISS改性后的滑带土,其进气值更高,且随着固结压力的增大,其进气值增幅较快。

3)开展ISS改性滑带土的非饱和土直剪试验,得出在同一垂直固结压力条件下,ISS改性滑带土的抗剪强度较大;随着基质吸力的增加,ISS改性滑带土的抗剪强度较高;但是土样的内摩擦角变化较小,粘聚力提高的较大。

4)通过对碎石含量、含水率、碎石粒径、分形特征、密实度等5个影响滑带土抗剪强度因素的试验,得出随着含石量的增加,ISS改性滑带土的抗剪强度效果越不显著;随着含水率的增加,ISS与滑带土的作用越充分,ISS改性滑带土的抗剪强度效果越显著;随着碎石粒径的增加,ISS改性滑带土的抗剪强度效果越不显著;随着分形维数的增加,ISS改性滑带土的抗剪强度效果越不显著;随着密实度的增加,ISS改性滑带土的抗剪强度效果越显著。

5ISS改性滑带土的渗透试验表明,ISS在滑带土中的渗流不符合达西线性渗流规律,随着渗流压力的增加,ISS在滑带土中渗流速度的增加幅度逐渐减小。在相同的水头高度条件下,ISS改性滑带土的渗流量减小。经ISS改性后,纯水在滑带土中的渗流量减小,渗流速度降低。

6分别对黄土坡滑坡滑带土进行了室内小型直剪实验以及粗粒土大型直剪实验。大型粗粒土直剪仪的剪切盒尺寸为500×500×400mm,室内实验尺寸直径为61.8mm,高度为20mm,试样尺寸相差很大。室内小型直剪实验所得到的抗剪强度参数C值和φ值分别为24kPa17.2°,而大型粗粒土直剪实验的C值为74kPa9.2-16.2°因此,采用小型直剪实验得出的抗剪强度结果作为滑带的抗剪强度不准确,而进行大尺寸实验研究更有实际意义

 

The National Natural Science Fund Project of large scale in-situ test of Ionic Soil Stabilizer (ISS) reinforcing sliding zone soil of Huangtupo landslide (No. 41002102) was finished by December 2013. The director of the project has finished the entire research plan in the project execution of January 2011 to December 2013. The following results have been achieved:

(1) The physical properties of sliding zone soil were obtained by the way of mixing of ISS and soil. The plastic index was discovered as the evaluation index of ISS reinforcing soil. There was a decreasing trend in bond water film as plastic index was decreased. There was no new mineral crystal appearing except the thinner interplanar spacing after reinforcing by the test of X-Ray diffraction. The content and category of cation change a lot after adding ISS. It illustrated that not only high polymer chemistry reaction, but also the cation exchange reaction is also under way. The microstructure of sliding zone soil appears face to face pile up with fewer pores.

(2) The compressibility coefficient was a decreasing trend after adding ISS according to the test of compressibility test, especially with rich clay content. It is to say ISS can change the bond water film so as to realign the clay particles. With the same compressibility pressure, the air suction was higher with add ISS than the simple soil. There was an increasing trend in air suction as the compressibility pressure was increased.

(3) The unsaturated soil direct shear test was carried out. The shear strength was higher after adding ISS in the same vertical compressibility pressure. There was an increasing trend in shear strength as the matric suction was increased. The inner friction angle change less but the cohesion force change more.

(4) By changing the influence factors of gravel content, water content, gravel grain size, fractal feather and density, the shear strength make a big change. There was an increasing trend in shear strength as the gravel content was decreased, as the water content was increased, as the gravel grain size was decreased, as the fracture feather was decreased and as the density was increased.

(5) The permeability test was carried out with adding ISS. The seepage is not conform to the Darcy law. The growing rate of seepage velocity was becoming less after adding ISS as the seepage pressure was increased. The seepage discharge was a decreasing trend after adding ISS with the same height of water head. After adding ISS, the seepage discharge of pure water in sliding zone soil decreased, the same as seepage velocity.

(6) The simple shear strength test and big scale shear strength were carried out. The sizes of shear box for big scale shear strength were 500×500×400mm, and diameter of 61.8mm and height of 20mm for small scale shear strength. The cohesion force and inner friction angle were 24kPa, 74kkPa and 17.2°, 9.2-16.2° for small scale and large scale respectively. It illustrated value of cohesion force was in the high side but the inner friction angle was in the low side for the large scale shear strength test. The conclusion was the large scale shear strength test was more practical significance than the small scale test indoor.

 

秭归实验室滑带土大尺寸剪切仪

GDS非饱和土三轴仪 

更多>>评论
发表评论
案例成果
更多>>联系我们

联系人:王老师
电 话:027-67885197
手 机:
邮 箱:
cugsoil@163.com
地 址:湖北省武汉市鲁磨路388号
邮 编:430074